The volunteer activities of healthcare executives

The role requirements of healthcare executives have received considerable attention from researchers; however, the volunteer efforts of executives have not been examined. This study investigates the relationship between an executive's position in the organizational hierarchy and his or her propensity to volunteer in general and to volunteer for the executive's professional society in particular. The study found that nearly all executives volunteered for some organization, but the type of work they performed was associated with their position level. For example, more than 90 percent of chief executive officers (CEOs) served on a board or a committee compared with less than half of mid-level executives. Also, more CEOs than lower-level executives were involved in fund-raising, setting professional standards, and testifying to legislatures. In general, we suggest that CEOs commit to volunteering, which facilitates their ability to achieve and retain their high-level position, recognition, and rewards. Fewer than half of the executives surveyed had volunteered for the American College of Healthcare Executives (ACHE), their professional society; the most common reasons given for not volunteering were lack of awareness of volunteer opportunities or not being asked to volunteer. Those that had volunteered for ACHE were primarily motivated by altruistic motives, such as the desire to help others, feelings of compassion for people in need, or the desire to do something for the profession. Career advancement was deemed to be a less important motivator in volunteering for ACHE. However, mid-level executives rated these motives more highly than did senior-level executives and CEOs. Because of the creation of local ACHE chapters, many more opportunities will become available for healthcare executives to volunteer for their professional society in the future.

To shatter the glass ceiling in healthcare management: who supports affirmative action and why?

We examined the findings of a recent national survey of healthcare executives that showed 90% of women but only 53% of men favoured efforts to increase the proportion of women in senior healthcare management positions. Using the theories of relative deprivation and social identity, we tested hypotheses to suggest the background, work characteristics and attitudes about existing discriminatory practices in their own organizations that correlate with respondents' views about affirmative action for women. Some support is evidenced for the two theories and explanations are suggested to account for apparent anomalies.

Fluorescence-based analyses of the effects of full-length recombinant TAF130p on the interaction of TATA box-binding protein with TATA box DNA

We have used a combination of fluorescence anisotropy spectroscopy and fluorescence-based native gel electrophoresis methods to examine the effects of the transcription factor IID-specific subunit TAF130p (TAF145p) upon the TATA box DNA binding properties of TATA box-binding protein (TBP). Purified full-length recombinant TAF130p decreases TBP-TATA DNA complex formation at equilibrium by competing directly with DNA for binding to TBP. Interestingly, we have found that full-length TAF130p is capable of binding multiple molecules of TBP with nanomolar binding affinity. The biological implications of these findings are discussed.

Molecular genetic dissection of TAF25, an essential yeast gene encoding a subunit shared by TFIID and SAGA multiprotein transcription factors

We have performed a systematic structure-function analysis of Saccharomyces cerevisiae TAF25, an evolutionarily conserved, single-copy essential gene which encodes the 206-amino-acid TAF25p protein. TAF25p is an integral subunit of both the 15-subunit general transcription factor TFIID and the multisubunit, chromatin-acetylating transcriptional coactivator SAGA. We used hydroxylamine mutagenesis, targeted deletion, alanine-scanning mutagenesis, high-copy suppression methods, and two-hybrid screening to dissect TAF25. Temperature-sensitive mutant strains generated were used for coimmunoprecipitation and transcription analyses to define the in vivo functions of TAF25p. The results of these analyses show that TAF25p is comprised of multiple mutable elements which contribute importantly to RNA polymerase II-mediated mRNA gene transcription.

Histone folds mediate selective heterodimerization of yeast TAF(II)25 with TFIID components yTAF(II)47 and yTAF(II)65 and with SAGA component ySPT7

We show that the yeast TFIID (yTFIID) component yTAF(II)47 contains a histone fold domain (HFD) with homology to that previously described for hTAF(II)135. Complementation in vivo indicates that the yTAF(II)47 HFD is necessary and sufficient for vegetative growth. Mutation of highly conserved residues in the alpha1 helix of the yTAF(II)47 HFD results in a temperature-sensitive phenotype which can be suppressed by overexpression of yTAF(II)25, as well as by yTAF(II)40, yTAF(II)19, and yTAF(II)60. In yeast two-hybrid and bacterial coexpression assays, the yTAF(II)47 HFD selectively heterodimerizes with yTAF(II)25, which we show contains an HFD with homology to the hTAF(II)28 family We additionally demonstrate that yTAF(II)65 contains a functional HFD which also selectively heterodimerizes with yTAF(II)25. These results reveal the existence of two novel histone-like pairs in yTFIID. The physical and genetic interactions described here show that the histone-like yTAF(II)s are organized in at least two substructures within TFIID rather than in a single octamer-like structure as previously suggested. Furthermore, our results indicate that ySPT7 has an HFD homologous to that of yTAF(II)47 which selectively heterodimerizes with yTAF(II)25, defining a novel histone-like pair in the SAGA complex.

Identification of two novel TAF subunits of the yeast Saccharomyces cerevisiae TFIID complex

Using a combination of ion exchange and immunoaffinity chromatography we have purified the general transcription initiation factor TFIID to near homogeneity from Saccharomyces cerevisiae. Yeast TFIID is composed of TBP, the TATA box binding protein, and 14 distinct TBP-associated factors (TAFs), which range in size from 17 to 150 kDa. Twelve of the TAF subunits have been previously identified, but two, TAF48p and TAF65p, are novel. TAF48p exhibits significant sequence similarity to the conserved C-terminal region of Drosophila TAF110p, human TAF130p, and human TAF105p and is encoded by a previously identified gene MPT1. TAF65p shows no significant sequence homology to any previously identified TAFp. The genes encoding TAF48p and TAF65p are single copy and essential for normal yeast cell growth. Furthermore, neither TAF48p nor TAF65p are associated with the histone acetylase Spt-Ada-Gcn5 complex or other non-TFIID TBF.TAF complexes. The significance of these results in terms of TFIID structure, function, and organization is discussed.

TAF25p, a non-histone-like subunit of TFIID and SAGA complexes, is essential for total mRNA gene transcription in vivo

We demonstrate, utilizing a temperature conditional mutant allele of the gene encoding TAF25p, that this non-histone-like TBP-associated factor, which is shared between the TFIID and SAGA complexes, is required for bulk mRNA gene transcription by RNA polymerase II in vivo. Immunoblotting experiments indicate that at the restrictive temperature, inactivation of TAF25p function results in a reduction of the levels of numerous TFIID and SAGA subunits, indicating its loss of function, like the histone-like TAFs, causes degradation of the constituents of these two multisubunit complexes. These data suggest that TAF25p plays a key structural role in maintaining TFIID and SAGA complex integrity. This is the first demonstration that a non-histone-like TAF is required for continuous, high level RNA polymerase II-mediated mRNA gene transcription in living yeast cells.

A model of voluntary turnover among hospital CEOs

This study examines factors contributing to hospital CEOs' voluntary decisions to leave their positions in 1990. Using a longitudinal design, we contrast 49 leavers with 1,362 stayers. We view turnover as influenced by both "push" factors that promote leaving (dissatisfaction with the position) and "hump" factors that need to be overcome (the cost of job change). Push factors giving rise to dissatisfaction include lower compensation, the predecessor's termination, and value incongruity between the CEO and the hospital. Testing the impact of key variables from Fiedler's contingency theory of leadership, we show that task-oriented leaders are relatively less satisfied when compared with relationship-oriented leaders. CEOs also express less satisfaction in low-situational control settings, a measure heavily influenced by perceived inadequate support from medical staff and subordinates. "Hump" factors that deterred leaving included family-related obstacles such as spouse's work or children's school, features mentioned most often by younger CEOs. The study suggests that boards should structure competitively paid positions with opportunities to generate support from the medical staff and subordinates. Recruiters for CEO positions are apprised of the importance of nonwork features in CEOs' willingness to consider new positions.

MOT1 can activate basal transcription in vitro by regulating the distribution of TATA binding protein between promoter and nonpromoter sites

MOT1 is an ATPase which can dissociate TATA binding protein (TBP)-DNA complexes in a reaction requiring ATP hydrolysis. Consistent with this observation, MOT1 can repress basal transcription in vitro. Paradoxically, however, some genes, such as HIS4, appear to require MOT1 as an activator of transcription in vivo. To further investigate the function of MOT1 in basal transcription, we performed in vitro transcription reactions using yeast nuclear extracts depleted of MOT1. Quantitation of MOT1 revealed that it is an abundant protein, with nuclear extracts from wild-type cells containing a molar excess of MOT1 over TBP. Surprisingly, MOT1 can weakly activate basal transcription in vitro. This activation by MOT1 is detectable with amounts of MOT1 that are approximately stoichiometric to TBP. With amounts of MOT1 similar to those present in wild-type nuclear extracts, MOT1 behaves as a weak repressor of basal transcription. These results suggest that MOT1 might activate transcription via an indirect mechanism in which limiting TBP can be liberated from nonpromoter sites for use at promoters. In support of this idea, excess nonpromoter DNA sequesters TBP and represses transcription, but this effect can be reversed by addition of MOT1. These results help to reconcile previous in vitro and in vivo results and expand the repertoire of transcriptional control strategies to include factor-assisted redistribution of TBP between promoter and nonpromoter sites.

A rapid technique for the determination of unknown plasmid library insert DNA sequence directly from intact yeast cells

A polymerase chain reaction (PCR)-based technique is described which allows for the determination of library plasmid insert DNA sequence directly and rapidly from intact yeast cells. Yeast spheroplasts are used to template a PCR reaction to amplify the insert sequence. This PCR product is then purified and its sequence directly determined using thermal cycle sequencing. Readable sequence can reproducibly be obtained from multiple yeast colonies in just two days. Uses of this technique in yeast two-hybrid screening as well as other types of yeast library screens are discussed.

ADR1-mediated transcriptional activation requires the presence of an intact TFIID complex

The yeast transcriptional activator ADR1, which is required for ADH2 and other genes' expression, contains four transactivation domains (TADs). While previous studies have shown that these TADs act through GCN5 and ADA2, and presumably TFIIB, other factors are likely to be involved in ADR1 function. In this study, we addressed the question of whether TFIID is also required for ADR1 action. In vitro binding studies indicated that TADI of ADR1 was able to retain TAFII90 from yeast extracts and TADII could retain TBP and TAFII130/145. TADIV, however, was capable of retaining multiple TAFIIs, suggesting that TADIV was binding TFIID from yeast whole-cell extracts. The ability of TADIV truncation derivatives to interact with TFIID correlated with their transcription activation potential in vivo. In addition, the ability of LexA-ADR1-TADIV to activate transcription in vivo was compromised by a mutation in TAFII130/145. ADR1 was found to associate in vivo with TFIID in that immunoprecipitation of either TAFII90 or TBP from yeast whole-cell extracts specifically coimmunoprecipitated ADR1. Most importantly, depletion of TAFII90 from yeast cells dramatically reduced ADH2 derepression. These results indicate that ADR1 physically associates with TFIID and that its ability to activate transcription requires an intact TFIID complex.

Biochemical and genetic characterization of the dominant positive element driving transcription ofthe yeast TBP-encoding gene, SPT15

We previously demonstrated that a combination of both positive and negative cis -acting upstream elements control the transcription of the gene encoding TBP ( SPT15 ) in Saccharomyces cerevisiae . One of these elements found in that study, resident between 5' flanking sequences -147 and -128 , and termed PED (for positive element distal), was found to play an essential positive role in driving transcription of the gene encoding TBP. In this report, we map at nucleotide-level resolution, the critical residues which comprise PED, purify and sequence the protein that binds to it and determine that this PED binding factor is Abf1p, an abundant yeast protein previously broadly implicated in both gene regulation and DNA replication. In the case of the TBP-encoding gene, however, Abf1p works through the PED element which is a non-consensus binding site. Based upon the work of others, the PED-variant ABF1 site would be predicted to be a very poor binding site for this factor yet Abf1p binds PED and a consensus ABF1 site with comparable affinity. These results are discussed in light of the broader context of Abf1p-mediated gene regulation.

Genetic tests of the role of Abf1p in driving transcription of the yeast TATA box bindng protein-encoding gene, SPT15

In this report we describe studies which utilized yeast strains bearing gain and loss of function alleles of ABF1 in order to attempt to directly implicate Abf1p in modulating transcription of the TBP-encoding gene, SPT15, in vivo. We found that overexpression of Abf1p in a yeast cell increased transcription of the TBP-encoding gene and that this stimulation depended upon the exact sequence of the Abf1p binding site (ABF1) present in the gene. Further, in a yeast strain expressing a temperature sensitive form of Abf1p, occupancy of the chromosomal ABF1 site in the TBP-encoding gene was immediately lost following a temperature shift. Both results suggest that Abf1p drives transcription of the TBP-encoding gene. Surprisingly though we found that continuous ABF1 cis-element occupancy by Abf1p was not acutely required for normal levels of transcription of either the TBP-encoding gene or other "Abf1p-driven" genes tested. We propose a model to explain these results and suggest mechanisms by which Abf1p could activate gene transcription.

The Gcn4p activation domain interacts specifically in vitro with RNA polymerase II holoenzyme, TFIID, and the Adap-Gcn5p coactivator complex

The Gcn4p activation domain contains seven clusters of hydrophobic residues that make additive contributions to transcriptional activation in vivo. We observed efficient binding of a glutathione S-transferase (GST)-Gcn4p fusion protein to components of three different coactivator complexes in Saccharomyces cerevisiae cell extracts, including subunits of transcription factor IID (TFIID) (yeast TAFII20 [yTAFII20], yTAFII60, and yTAFII90), the holoenzyme mediator (Srb2p, Srb4p, and Srb7p), and the Adap-Gcn5p complex (Ada2p and Ada3p). The binding to these coactivator subunits was completely dependent on the hydrophobic clusters in the Gcn4p activation domain. Alanine substitutions in single clusters led to moderate reductions in binding, double-cluster substitutions generally led to greater reductions in binding than the corresponding single-cluster mutations, and mutations in four or more clusters reduced binding to all of the coactivator proteins to background levels. The additive effects of these mutations on binding of coactivator proteins correlated with their cumulative effects on transcriptional activation by Gcn4p in vivo, particularly with Ada3p, suggesting that recruitment of these coactivator complexes to the promoter is a cardinal function of the Gcn4p activation domain. As judged by immunoprecipitation analysis, components of the mediator were not associated with constituents of TFIID and Adap-Gcn5p in the extracts, implying that GST-Gcn4p interacted with the mediator independently of these other coactivators. Unexpectedly, a proportion of Ada2p coimmunoprecipitated with yTAFII90, and the yTAFII20, -60, and -90 proteins were coimmunoprecipitated with Ada3p, revealing a stable interaction between components of TFIID and the Adap-Gcn5p complex. Because GST-Gcn4p did not bind specifically to highly purified TFIID, Gcn4p may interact with TFIID via the Adap-Gcn5p complex or some other adapter proteins. The ability of Gcn4p to interact with several distinct coactivator complexes that are physically and genetically linked to TATA box-binding protein can provide an explanation for the observation that yTAFII proteins are dispensable for activation by Gcn4p in vivo.

Structure-function analysis of TAF130: identification and characterization of a high-affinity TATA-binding protein interaction domain in the N terminus of yeast TAF(II)130

We report structure-function analyses of TAF130, the single-copy essential yeast gene encoding the 130,000-Mr yeast TATA-binding protein (TBP)-associated factor TAF(II)130 (yTAF(II)130). A systematic family of TAF130 mutants was generated, and these mutant TAF130 alleles were introduced into yeast in both single and multiple copies to test for their ability to complement a taf130delta null allele and support cell growth. All mutant proteins were stably expressed in vivo. The complementation tests indicated that a large portion (amino acids 208 to 303 as well as amino acids 367 to 1037) of yTAF(II)130 is required to support cell growth. Direct protein blotting and coimmunoprecipitation analyses showed that two N-terminal deletions which remove portions of yTAF(II)130 amino acids 2 to 115 dramatically decrease the ability of these mutant yTAF(II)130 proteins to bind TBP. Cells bearing either of these two TAF130 mutant alleles also exhibit a slow-growth phenotype. Consistent with these observations, overexpression of TBP can correct this growth deficiency as well as increase the amount of TBP interacting with yTAF(II)130 in vivo. Our results provide the first combined genetic and biochemical evidence that yTAF(II)130 binds to yeast TBP in vivo through yTAF(II)130 N-terminal sequences and that this binding is physiologically significant. By using fluorescence anisotropy spectroscopic binding measurements, the affinity of the interaction of TBP for the N-terminal TBP-binding domain of yTAF(II)130 was measured, and the Kd was found to be about 1 nM. Moreover, we found that the N-terminal domain of yTAF(II)130 actively dissociated TBP from TATA box-containing DNA.

Cloning and characterization of an essential Saccharomyces cerevisiae gene, TAF40, which encodes yTAFII40, an RNA polymerase II-specific TATA-binding protein-associated factor

In this report we describe the cloning and initial characterization of TAF40, a gene that encodes a yeast TATA-binding protein-associated factor (yTAF) of Mr = approximately 40,000. This gene has many similarities to other yTAFs described thus far in that it is present at a single copy per haploid genome, it is essential for viability, and the deduced protein sequence of yTAF40 exhibits similarity to previously described human and Drosophila TAFIIs. Immunological studies confirm that yTAF40 protein is a subunit of a large multiprotein TATA-binding protein-TAF complex that contains a subset of the total number of the yTAFs present in yeast cell extracts. Transcription reactions performed using yeast whole cell extracts reveal that of the three nuclear RNA polymerases only RNA polymerase II function is abrogated when yTAF40 and associated proteins are immunodepleted from solution, indicating that the functionality of the multiprotein complex containing yTAF40 is RNA polymerase II-specific. By these criteria yTAF40 appears to encode a bona fide RNA polymerase II-specific TAF, and thus the protein that it encodes has been termed yTAFII40.

Molecular genetic elucidation of the tripartite structure of the Schizosaccharomyces pombe 72 kDa TFIID subunit which contains a WD40 structural motif

BACKGROUND

The multisubunit general transcription factor termed TFIID is comprised of the TATA box DNA binding protein TBP and several TBP-associated factors termed TAFs. Current arguments regarding the mechanisms of regulation of transcription contend that TFIID makes multiple specific protein-protein interactions with numerous protein factors, and that these interactions are important for the regulation of transcriptional initiation. TAFs contain a variety of potential structural motifs and it has been speculated that these motifs participate directly in TAF function. However, to date the physiological significance of these putative structural motifs has not been systematically analysed in vivo.

RESULTS

The essential gene encoding the Schizosaccharomyces pombe 72 kDa TFIID subunit is termed taf72+, which contains WD40 repeats, was cloned and sequenced. A comparison of the primary structure of this gene with its Drosophila and S. cerevisiae counterparts suggests the presence of regions that might play a role in TFIID function, due to the fact that significant portions of the sequences are highly conserved. Complementation analyses of a series of deletion mutants of this gene revealed that the most evolutionarily conserved regions of taf72+, including the WD40 repeats, are in fact indispensable for the viability.

CONCLUSIONS

The 72 kDa subunit of S. pombe TFIID, which contains putative WD40 repeats, consists of three distinct functional domains separated by intervening regions. The functional significance of the WD40 repeats is demonstrated by this in vivo study.

TBP-associated factors are not generally required for transcriptional activation in yeast

The transcription factor TFIID, a central component of the eukaryotic RNA polymerase II (Pol II) transcription apparatus, comprises the TATA-binding protein (TBP) and approximately ten TBP-associated factors (TAFs). Although the essential role of TBP in all eukaryotic transcription has been extensively analysed in vivo and in vitro, the function of the TAFs is less clear. In vitro, TAFs are dispensable for basal transcription but are required for the response to activators. In addition, specific TAFs may act as molecular bridges between particular activators and the general transcription machinery. In vivo, TAFS are required for yeast and mammalian cell growth, but little is known about their specific transcriptional functions. Using conditional alleles created by a new double-shutoff method, we show here that TAF depletion in yeast cells can reduce transcription from some promoters lacking conventional TATA elements. However, TAF depletion has surprisingly little effect on transcriptional enhancement by several activators, indicating that TAFs are not generally required for transcriptional activation in yeast.

Isolation and characterization of TAF25, an essential yeast gene that encodes an RNA polymerase II-specific TATA-binding protein-associated factor

We describe the cloning and analysis of TAF25, a previously uncharacterized yeast gene that encodes a yeast TATA-binding protein-associated factor or yTAF of Mr = 25,000. The gene encoding yTAF25 is a single copy essential gene, and the protein sequence deduced from TAF25 exhibits sequence similarity to a metazoan hTAFII. The results from immunological studies confirm that yTAF25 is a subunit of a large multiprotein TATA-binding protein-yeast TATA-binding protein-associated factor complex that contains a subset of the total number of the yTAFs present in yeast cell extracts. Both genetic and biochemical analyses demonstrate that yTAF25 can interact directly with itself. Transcriptional data show that the activity of the multiprotein complex containing yTAF25 is RNA polymerase II-specific, thus indicating that TAF25 encodes a bona fide yeast RNA polymerase II TAF. Hence the protein encoded by TAF25 has been termed yTAFII25.

Identification and characterization of a TFIID-like multiprotein complex from Saccharomyces cerevisiae

Although the mechanisms of transcriptional regulation by RNA polymerase II are apparently highly conserved from yeast to man, the identification of a yeast TATA-binding protein (TBP)-TBP-associated factor (TAFII) complex comparable to the metazoan TFIID component of the basal transcriptional machinery has remained elusive. Here, we report the isolation of a yeast TBP-TAFII complex which can mediate transcriptional activation by GAL4-VP16 in a highly purified yeast in vitro transcription system. We have cloned and sequenced the genes encoding four of the multiple yeast TAFII proteins comprising the TBP-TAFII multisubunit complex and find that they are similar at the amino acid level to both human and Drosophila TFIID subunits. Using epitope-tagging and immunoprecipitation experiments, we demonstrate that these genes encode bona fide TAF proteins and show that the yeast TBP-TAFII complex is minimally composed of TBP and seven distinct yTAFII proteins ranging in size from M(r) = 150,000 to M(r) = 25,000. In addition, by constructing null alleles of the cloned TAF-encoding genes, we show that normal function of the TAF-encoding genes is essential for yeast cell viability.

Yeast TATA binding protein interaction with DNA: fluorescence determination of oligomeric state, equilibrium binding, on-rate, and dissociation kinetics

A combination of steady-state, stopped-flow, and time-resolved fluorescence of intrinsic tryptophan and extrinsically labeled fluorescent DNA is utilized to examine the interaction of yeast TATA binding protein (TBP) with DNA. TBP is composed of two structural domains, the carboxy domain (residues 61-240), which is responsible for DNA binding and initiation of basal level transcription, and an amino terminal domain (residues 1-60), whose function is currently unknown. The steady-state fluorescence emission spectrum of the single tryptophan in the amino terminal domain of TBP undergoes a huge (30-40 nm) red-shift upon interaction with stoichiometric amounts of TATA box containing DNA. From time-resolved tryptophan fluorescence anisotropy studies, we demonstrate that, in the absence of DNA, the protein exists as a multimer in solution and it contains (at least) two primary conformations, one with the amino terminus associated tightly with the protein(s) in a hydrophobic environment and one with the amino terminus decoupled away from the rest of the protein and solvent-exposed. Upon binding DNA, the protein dissociates into a monomeric complex, upon which only the solvent-exposed amino terminus conformation remains. Kinetic and equilibrium binding studies were performed on TATA box containing DNA which was extrinsically labeled with a fluorescent probe Rhodamine-X at the 5'-end. This "fluorescent" DNA allowed for the collection of quantitative spectroscopic binding, kinetic on-rate, and kinetic off-rate data at physiological concentrations. Global analysis of equilibrium binding studies performed from 500 pM to 50 nM DNA reveals a single dissociation constant (Kd) of approximately 5 nM. Global analysis of stopped-flow anisotropy on-rate experiments, with millisecond timing resolution and TBP concentrations ranging from 20 to 600 nM (20 nM DNA), can be perfectly described by a single second-order rate constant of 1.66 x 10(5) M(-1) s(-1). These measurements represent the very first stopped-flow anisotropy study of a protein/DNA interaction. Stopped-flow anisotropy off-rate experiments reveal a single exponential k(off) of 4.3 x 10(-2) min-1 (1/k(off) = 23 min) From the ratio of on-rate to off-rate, a predicted Kd of 4.3 nM is obtained, revealing that the kinetic and equilibrium studies are internally consistent. Deletion of the amino terminal domain of TBP decreases the k(on) of TBP approximately 45-fold and eliminates classic second-order behavior.

Correlates of hospital leadership team effectiveness: results of a national survey of board chairmen

To examine hospital leadership team effectiveness, analyses the responses of 540 randomly sampled board chairmen of US hospitals. Reports findings regarding board chairmen's evaluation of their hospitals' productive outputs and of the adequacy of their communications with the CEO and medical staff president (MSP) in their hospitals. Notes that over one-quarter of board chairmen found communications with the MSP to be only sometimes productive and notes means whereby positive communications are promoted. Offers suggestions for board chairmen recruitment.

TFIIF-TAF-RNA polymerase II connection

RNA polymerase transcription factor IIF (TFIIF) is required for initiation at most, if not all, polymerase II promoters. We report here the cloning and sequencing of genes for a yeast protein that is the homolog of mammalian TFIIF. This yeast protein, previously designated factor g, contains two subunits, Tfg1 and Tfg2, both of which are required for transcription, essential for yeast cell viability, and whose sequences exhibit significant similarity to those of the mammalian factor. The yeast protein also contains a third subunit, Tfg3, which is less tightly associated and at most stimulatory to transcription, dispensable for cell viability, and has no known counterpart in mammalian TFIIF. Remarkably, the TFG3 gene encodes yeast TAF30, and furthermore, is identical to ANC1, a gene implicated in actin cytoskeletal function in vivo (Welch and Drubin 1994). Tfg3 is also a component of the recently described mediator complex (Kim et al. 1994), whose interaction with the carboxy-terminal repeat domain of RNA polymerase II enables transcriptional activation. Deletion of TFG3 results in diminished transcription in vivo.

Identification of the cis-acting DNA sequence elements regulating the transcription of the Saccharomyces cerevisiae gene encoding TBP, the TATA box binding protein

TBP, the TATA-box binding protein, plays a key role in eukaryotic gene transcription since it is required for transcription initiation by all three eukaryotic nuclear DNA-dependent RNA polymerases. In order to gain insight into the mechanisms of regulation of this key basal transcription factor, we undertook a mutational analysis of the sequences involved in directing transcription of the gene encoding TBP in Saccharomyces cerevisiae. An extensive family of mutations in the promoter of the gene encoding TBP were fused to the Escherichia coli reporter gene lacZ, transferred back into yeast, and assayed for their ability to direct expression of beta-galactosidase. Levels of beta-galactosidase activity measured from yeast transformed with this family of constructs indicate that both positive- and negative-acting cis-elements located within 400 nucleotides of the transcription start site are involved in regulating transcription of the TBP-encoding gene. Analyses of RNA prepared from these same cells showed that specific transcription initiation is maintained in the mutant reporter constructs and that RNA levels mirror beta-galactosidase levels. In order to corroborate the results of these mutational analyses of the TBP-encoding gene, in vivo cis-element occupancy was examined using several different footprinting reagents. The patterns of protection observed demonstrated that the sequence elements implicated in the control of TBP gene transcription by reporter gene analyses appear to be bound by protein(s) in vivo. Interesting sequence similarities were noted between two TBP-gene regulatory elements and 5'-flanking sequences of genes encoding several other basal transcription factors.

The governance team. A firsthand look at leadership practices

Findings from Phase 1 of the Partnership Study--a national, random sample of board chairmen, chief executive officers and medical staff presidents--paint a detailed picture of national practices of hospital governance teams. In addition, the findings point to a number of inconsistencies regarding the views that board chairmen, CEOs and medical staff presidents have about their leadership roles. Conducted by the American College of Healthcare Executives (ACHE), the American Hospital Association, the American Medical Association and Ernst & Young, Phase 1 Partnership Study findings were reported in the January issue of Trustee (page 16). In Phase 2, of the Partnership Study, in-depth case studies were conducted to address these questions: How do the board chairman, CEO and medical staff president interact one-on-one and as group? How do these three health care leaders perceive one another? What attributes of effective working relationships exist among the three leaders? To answer these questions, confidential site visits were made to six hospitals identified in this article as Metropolitan, North Woods, Midwest, Suncoast, Mountain Valley and Southland (see Study Sites, page 13). Following are some preliminary impressions, based on five completed case-study site visits. The sixth study site visit was in progress at press time.

Isolation and characterization of a novel transcription factor that binds to and activates insulin control element-mediated expression

Pancreatic beta-cell-type-specific transcription of the insulin gene is principally regulated by a single cis-acting DNA sequence element, termed the insulin control element (ICE), which is found within the 5'-flanking region of the gene. The ICE activator is a heteromeric complex composed of an islet alpha/beta-cell-specific factor associated with the ubiquitously distributed E2A-encoded proteins (E12, E47, and E2-5). We describe the isolation and characterization of a cDNA for a protein present in alpha and beta cells, termed INSAF for insulin activator factor, which binds to and activates ICE-mediated expression. INSAF was isolated from a human insulinoma cDNA library. Transfection experiments demonstrated that INSAF activates ICE expression in insulin-expressing cells but not in non-insulin-expressing cells. Cotransfection experiments showed that activation by INSAF was inhibited by Id, a negative regulator of basic helix-loop-helix (bHLH) protein function. INSAF was also shown to associate in vitro with the bHLH protein E12. In addition, affinity-purified INSAF antiserum abolished the formation of the activator-specific ICE-binding complex. Immunohistochemical studies indicate that INSAF is restricted in terms of its expression pattern, in that INSAF appears to be detected only within the nuclei of islet pancreatic alpha and beta cells. All of these data are consistent with the proposal that INSAF is either part of the ICE activator or is antigenically related to the specific activator required for insulin gene transcription.

Yeast Taf170 is encoded by MOT1 and exists in a TATA box-binding protein (TBP)-TBP-associated factor complex distinct from transcription factor IID

Our characterization of the Saccharomyces cerevisiae TATA box-binding protein (TBP) has led to the identification of nine specific yeast TBP-associated factors (TAFs) ranging in size from 170 to 25 kDa. The amino acid sequence derived from a purified TAF with an apparent M(r) of 170,000 indicates that yeast Taf170 is encoded by the essential yeast gene MOT1. We describe in this report a series of experiments that demonstrate that the protein encoded by MOT1 is a bona fide yeast TAF and that Taf170 forms a separate complex with TBP distinct from the RNA polymerase II-specific multisubunit transcription factor IID TBP-TAF complex. The significance of this unique TBP-Taf170 complex regarding transcriptional regulation is discussed.

Binding of TFIID and MEF2 to the TATA element activates transcription of the Xenopus MyoDa promoter

Members of the MyoD family of helix-loop-helix proteins control expression of the muscle phenotype by regulating the activity of subordinate genes. To investigate processes that control the expression of myogenic factors and regulate the establishment and maintenance of the skeletal muscle phenotype, we have analyzed sequences necessary for transcription of the maternally expressed Xenopus MyoD (XMyoD) gene. A 3.5-kb DNA fragment containing the XMyoDa promoter was expressed in a somite-specific manner in injected frog embryos. The XMyoDa promoter was active in oocytes and cultured muscle cells but not in fibroblasts or nonmuscle cell lines. A 58-bp fragment containing the transcription initiation site, a GC-rich region, and overlapping binding sites for the general transcription factor TFIID and the muscle-specific factor MEF2 was sufficient for muscle-specific transcription. Transcription of the minimal XMyoDa promoter in nonmuscle cells was activated by expression of Xenopus MEF2 (XMEF2) and required binding of both MEF2 and TFIID to the TATA motif. These results demonstrate that the XMyoDa TATA motif is a target for a cell-type-specific regulatory factor and suggests that MEF2 stabilizes and amplifies XMyoDa transcription in mesodermal cells committed to the muscle phenotype.

Immunopurification of yeast TATA-binding protein and associated factors. Presence of transcription factor IIIB transcriptional activity

The TATA-binding proteins (TBP) from both human and Drosophila have been shown to exist in various distinct multiprotein complexes that are required, respectively, for transcription by all three RNA polymerases. In contrast, in vitro biochemical analyses have suggested that yeast TBP exists as a monomeric 27-kDa protein free in solution. We have examined the oligomerization state of yeast TBP and report here that yeast TBP, like human and Drosophila TBPs, is also stably associated with other proteins in vitro. Using anti-TBP antibodies we have immunopurified yeast TBP and associated factors (TBP-associated factors or TAFs). When this fraction was analyzed by SDS-polyacrylamide gel electrophoresis, polypeptides of approximate relative molecular size ranging from 170 to 60 kDa are prominently represented. Immunoblot analysis revealed that one of these TAFs, TAF70, corresponds to BRF1/TDS4/PCF4, a subunit of transcription factor (TF) IIIB. Furthermore, this highly purified TAF fraction can reconstitute polymerase III transcription when supplemented with purified RNA polymerase III and TFIIIC. Our data indicate that our TAF fraction contains TFIIIB transcription factor activity and that all the subunits of yeast TFIIIB are stably complexed with TBP.

Genetic and biochemical analyses of yeast TATA-binding protein mutants

We have taken a combined genetic and biochemical approach to study TATA-binding protein (TBP) structure-function relationships. Using site-directed mutagenesis coupled with a screen for conditional lethal growth, we have isolated a number of temperature-sensitive TBP alleles in the region of amino acid positions 188, 189, and 190. Conditional growth is not a result of increased TBP turnover as most of the mutant proteins are stable in vivo as evidenced by immunoblot detection of TBP steady-state levels. DNA binding assays reveal that mutations at position 188 do not affect DNA binding activity of these mutants, even at high temperatures. Utilizing whole cell extracts which contain mutant TBPs in in vitro transcription experiments, we confirm that TBP is required for transcription by all three nuclear polymerases. However, certain of our TBP mutants are only compromised for RNA polymerase II transcription.

A bipartite DNA binding domain composed of direct repeats in the TATA box binding factor TFIID

Point mutations in residues comprising the interrupted direct repeats of TFIID eliminated DNA binding in an electrophoretic mobility shift assay. In contrast, mutations in nonconserved residues within the direct repeat regions or in lysine residues comprising the intervening basic repeat had no effect on DNA binding. However, small spacing changes (addition or deletion of one to three residues) in the basic repeat eliminated DNA binding. These results argue for a bipartite DNA binding domain composed of direct repeats with a strict spacing and orientation. Surprisingly, some direct repeat mutations that inhibited DNA binding failed to show a corresponding inhibition of basal transcription, indicating compensating interactions of TFIID with other general factors. The implications of these and other recent results for TFIID structure, promoter recognition, and interactions with other factors are discussed.

Cloning of TFC1, the Saccharomyces cerevisiae gene encoding the 95-kDa subunit of transcription factor TFIIIC

The yeast gene encoding the 95-kDa subunit of the class III gene transcription factor TFIIIC was cloned. This gene, termed TFC1 (transcription factor C, gene 1), was isolated by screening a lambda gt11 yeast cDNA expression library using a polyclonal antiserum preparation which was previously shown to specifically recognize the 95-kDa subunit of yeast TFIIIC (Parsons, M. C., and Weil, P. A. (1990) J. Biol. Chem. 265, 5095-5103). TFC1 was found to be a single copy gene which contained a continuous open reading frame about 2 kilobases in length. TFC1 was shown to encode the 95-kDa subunit of TFIIIC by several criteria. Like the authentic yeast protein, the protein encoded by TFC1 had an apparent molecular weight of 95,000. In addition, the protein encoded by the TFC1 gene bound to the same antibody species as the yeast 95-kDa subunit of TFIIIC. Last, the sizes of the cleavage products of the Escherichia coli-expressed protein were indistinguishable from those of the cleavage products of the bona fide yeast 95-kDa protein.

The conserved carboxy-terminal domain of Saccharomyces cerevisiae TFIID is sufficient to support normal cell growth

We have examined the structure-function relationships of TFIID through in vivo complementation tests. A yeast strain was constructed which lacked the chromosomal copy of SPT15, the gene encoding TFIID, and was therefore dependent on a functional plasmid-borne wild-type copy of this gene for viability. By using the plasmid shuffle technique, the plasmid-borne wild-type TFIID gene was replaced with a family of plasmids containing a series of systematically mutated TFIID genes. These various forms of TFIID were expressed from three different promoter contexts of different strengths, and the ability of each mutant form of TFIID to complement our chromosomal TFIID null allele was assessed. We found that the first 61 amino acid residues of TFIID are totally dispensable for vegetative cell growth, since yeast strains containing this deleted form of TFIID grow at wild-type rates. Amino-terminally deleted TFIID was further shown to be able to function normally in vivo by virtue of its ability both to promote accurate transcription initiation from a large number of different genes and to interact efficiently with the Gal4 protein to activate transcription of GAL1 with essentially wild-type kinetics. Any deletion removing sequences from within the conserved carboxy-terminal region of S. cerevisiae TFIID was lethal. Further, the exact sequence of the conserved carboxy-terminal portion of the molecule is critical for function, since of several heterologous TFIID homologs tested, only the highly related Schizosaccharomyces pombe gene could complement our S. cerevisiae TFIID null mutant. Taken together, these data indicate that all important functional domains of TFIID appear to lie in its carboxy-terminal 179 amino acid residues. The significance of these findings regarding TFIID function are discussed.

Insulin gene expression in nonexpressing cells appears to be regulated by multiple distinct negative-acting control elements

Selective transcription of the insulin gene in pancreatic beta cells is regulated by its enhancer, located between nucleotides -340 and -91 relative to the transcription start site. Transcription from the enhancer is controlled by both positive- and negative-acting cellular factors. Cell-type-specific expression is mediated principally by a single cis-acting enhancer element located between -100 and -91 in the rat insulin II gene (referred to as the insulin control element [ICE]), which is acted upon by both of these cellular activities. Analysis of the effect of 5' deletions within the insulin enhancer has identified a region between nucleotides -217 and -197 that is also a site of negative control. Deletion of these sequences from the 5' end of the enhancer leads to transcription of the enhancer in non-insulin-producing cells, even though the ICE is intact. Derepression of this ICE-mediated effect was shown to be due to the binding of a ubiquitously distributed cellular factor to a sequence element which resides just upstream of the ICE (i.e., between nucleotides -110 and -100). We discuss the possible relationship of these results to cell-type-specific regulation of the insulin gene.