1
|
Chi BB, Lu YN, Yin PC, Liu HY, Chen HY, Shan Y. Sequencing and Comparative Genomic Analysis of a Highly Metal-Tolerant Penicillium janthinellum P1 Provide Insights Into Its Metal Tolerance. Front Microbiol 2021; 12:663217. [PMID: 34149650 PMCID: PMC8212970 DOI: 10.3389/fmicb.2021.663217] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 05/14/2021] [Indexed: 12/13/2022] Open
Abstract
Heavy metal pollution is a global knotty problem and fungi hold promising potential for the remediation of wastewater containing heavy metals. Here, a new highly chromium-tolerance species, Penicillium janthinellum P1, is investigated. The genome of P1 was sequenced and assembled into 30 Mb genome size containing 10,955 predicted protein-coding genes with a GC content of 46.16% through an integrated method of Illumina short-read sequencing and single-molecule real-time Pacific Biosciences sequencing platforms. Through a phylogenetic analysis with model species of fungi, the evolutionary divergence time of Penicillium janthinellum P1 and Penicillium oxalicum 114-2 was estimated to be 74 MYA. 33 secondary metabolism gene clusters were identified via antiSMASH software, mainly including non-ribosomal peptide synthase genes and T1 polyketide synthase genes. 525 genes were annotated to encode enzymes that act on carbohydrates, involving 101 glucose-degrading enzymes and 24 polysaccharide synthase. By whole-genome sequence analysis, large numbers of metal resistance genes were found in strain P1. Especially ABC transporter and Superoxide dismutase ensure that the P1 fungus can survive in a chromium-polluted environment. ChrA and ChrR were also identified as key genes for chromium resistance. Analysis of their genetic loci revealed that the specific coding-gene arrangement may account for the fungus’s chromium resistance. Genetic information and comparative analysis of Penicillium janthinellum are valuable for further understanding the mechanism of high resistance to heavy metal chromium, and gene loci analysis provides a new perspective for identifying chromium-resistant strains.
Collapse
Affiliation(s)
- Bin-Bin Chi
- College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China.,Guangxi Key Laboratory of Electrochemical and Magneto-Chemical Functional Materials, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China
| | - Ya-Nan Lu
- College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China.,Guangxi Key Laboratory of Electrochemical and Magneto-Chemical Functional Materials, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China
| | - Ping-Chuan Yin
- College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China.,Guangxi Key Laboratory of Electrochemical and Magneto-Chemical Functional Materials, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China
| | - Hong-Yan Liu
- College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China.,Guangxi Key Laboratory of Electrochemical and Magneto-Chemical Functional Materials, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China
| | - Hui-Ying Chen
- College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China.,Guangxi Key Laboratory of Electrochemical and Magneto-Chemical Functional Materials, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China
| | - Yang Shan
- Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| |
Collapse
|
2
|
Sequential activation of human signal recognition particle by the ribosome and signal sequence drives efficient protein targeting. Proc Natl Acad Sci U S A 2018; 115:E5487-E5496. [PMID: 29848629 DOI: 10.1073/pnas.1802252115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Signal recognition particle (SRP) is a universally conserved targeting machine that mediates the targeted delivery of ∼30% of the proteome. The molecular mechanism by which eukaryotic SRP achieves efficient and selective protein targeting remains elusive. Here, we describe quantitative analyses of completely reconstituted human SRP (hSRP) and SRP receptor (SR). Enzymatic and fluorescence analyses showed that the ribosome, together with a functional signal sequence on the nascent polypeptide, are required to activate SRP for rapid recruitment of the SR, thereby delivering translating ribosomes to the endoplasmic reticulum. Single-molecule fluorescence spectroscopy combined with cross-complementation analyses reveal a sequential mechanism of activation whereby the ribosome unlocks the hSRP from an autoinhibited state and primes SRP to sample a variety of conformations. The signal sequence further preorganizes the mammalian SRP into the optimal conformation for efficient recruitment of the SR. Finally, the use of a signal sequence to activate SRP for receptor recruitment is a universally conserved feature to enable efficient and selective protein targeting, and the eukaryote-specific components confer upon the mammalian SRP the ability to sense and respond to ribosomes.
Collapse
|
3
|
Kobayashi K, Jomaa A, Lee JH, Chandrasekar S, Boehringer D, Shan SO, Ban N. Structure of a prehandover mammalian ribosomal SRP·SRP receptor targeting complex. Science 2018; 360:323-327. [PMID: 29567807 PMCID: PMC6309883 DOI: 10.1126/science.aar7924] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/12/2018] [Indexed: 01/13/2023]
Abstract
Signal recognition particle (SRP) targets proteins to the endoplasmic reticulum (ER). SRP recognizes the ribosome synthesizing a signal sequence and delivers it to the SRP receptor (SR) on the ER membrane followed by the transfer of the signal sequence to the translocon. Here, we present the cryo-electron microscopy structure of the mammalian translating ribosome in complex with SRP and SR in a conformation preceding signal sequence handover. The structure visualizes all eukaryotic-specific SRP and SR proteins and reveals their roles in stabilizing this conformation by forming a large protein assembly at the distal site of SRP RNA. We provide biochemical evidence that the guanosine triphosphate hydrolysis of SRP·SR is delayed at this stage, possibly to provide a time window for signal sequence handover to the translocon.
Collapse
Affiliation(s)
- Kan Kobayashi
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, Zurich CH-8093, Switzerland
| | - Ahmad Jomaa
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, Zurich CH-8093, Switzerland
| | - Jae Ho Lee
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Sowmya Chandrasekar
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Daniel Boehringer
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, Zurich CH-8093, Switzerland
| | - Shu-Ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, Zurich CH-8093, Switzerland.
| |
Collapse
|
4
|
Protein-borne methionine residues as structural antioxidants in mitochondria. Amino Acids 2015; 47:1421-32. [DOI: 10.1007/s00726-015-1955-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 03/03/2015] [Indexed: 01/25/2023]
|
5
|
Peng Q, Yuan Y, Gao M, Chen X, Liu B, Liu P, Wu Y, Wu D. Genomic characteristics and comparative genomics analysis of Penicillium chrysogenum KF-25. BMC Genomics 2014; 15:144. [PMID: 24555742 PMCID: PMC3938070 DOI: 10.1186/1471-2164-15-144] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 02/06/2014] [Indexed: 12/14/2022] Open
Abstract
Background Penicillium chrysogenum has been used in producing penicillin and derived β-lactam antibiotics for many years. Although the genome of the mutant strain P. chrysogenum Wisconsin 54-1255 has already been sequenced, the versatility and genetic diversity of this species still needs to be intensively studied. In this study, the genome of the wild-type P. chrysogenum strain KF-25, which has high activity against Ustilaginoidea virens, was sequenced and characterized. Results The genome of KF-25 was about 29.9 Mb in size and contained 9,804 putative open reading frames (orfs). Thirteen genes were predicted to encode two-component system proteins, of which six were putatively involved in osmolarity adaption. There were 33 putative secondary metabolism pathways and numerous genes that were essential in metabolite biosynthesis. Several P. chrysogenum virus untranslated region sequences were found in the KF-25 genome, suggesting that there might be a relationship between the virus and P. chrysogenum in evolution. Comparative genome analysis showed that the genomes of KF-25 and Wisconsin 54-1255 were highly similar, except that KF-25 was 2.3 Mb smaller. Three hundred and fifty-five KF-25 specific genes were found and the biological functions of the proteins encoded by these genes were mainly unknown (232, representing 65%), except for some orfs encoding proteins with predicted functions in transport, metabolism, and signal transduction. Numerous KF-25-specific genes were found to be associated with the pathogenicity and virulence of the strains, which were identical to those of wild-type P. chrysogenum NRRL 1951. Conclusion Genome sequencing and comparative analysis are helpful in further understanding the biology, evolution, and environment adaption of P. chrysogenum, and provide a new tool for identifying further functional metabolites.
Collapse
Affiliation(s)
| | | | - Meiying Gao
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
| | | | | | | | | | | |
Collapse
|
6
|
Anti-cooperative assembly of the SRP19 and SRP68/72 components of the signal recognition particle. Biochem J 2008; 415:429-37. [PMID: 18564060 DOI: 10.1042/bj20080569] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The mammalian SRP (signal recognition particle) represents an important model for the assembly and role of inter-domain interactions in complex RNPs (ribonucleoproteins). In the present study we analysed the interdependent interactions between the SRP19, SRP68 and SRP72 proteins and the SRP RNA. SRP72 binds the SRP RNA largely via non-specific electrostatic interactions and enhances the affinity of SRP68 for the RNA. SRP19 and SRP68 both bind directly and specifically to the same two RNA helices, but on opposite faces and at opposite ends. SRP19 binds at the apices of helices 6 and 8, whereas the SRP68/72 heterodimer binds at the three-way junction involving RNA helices 5, 6 and 8. Even though both SRP19 and SRP68/72 stabilize a similar parallel orientation for RNA helices 6 and 8, these two proteins bind to the RNA with moderate anti-cooperativity. Long-range anti-cooperative binding by SRP19 and SRP68/72 appears to arise from stabilization of distinct conformations in the stiff intervening RNA scaffold. Assembly of large RNPs is generally thought to involve either co-operative or energetically neutral interactions among components. By contrast, our findings emphasize that antagonistic interactions can play significant roles in assembly of multi-subunit RNPs.
Collapse
|
7
|
Iakhiaeva E, Bhuiyan SH, Yin J, Zwieb C. Protein SRP68 of human signal recognition particle: identification of the RNA and SRP72 binding domains. Protein Sci 2006; 15:1290-302. [PMID: 16672232 PMCID: PMC2242529 DOI: 10.1110/ps.051861406] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The signal recognition particle (SRP) plays an important role in the delivery of secretory proteins to cellular membranes. Mammalian SRP is composed of six polypeptides among which SRP68 and SRP72 form a heterodimer that has been notoriously difficult to investigate. Human SRP68 was purified from overexpressing Escherichia coli cells and was found to bind to recombinant SRP72 as well as in vitro-transcribed human SRP RNA. Polypeptide fragments covering essentially the entire SRP68 molecule were generated recombinantly or by proteolytic digestion. The RNA binding domain of SRP68 included residues from positions 52 to 252. Ninety-four amino acids near the C terminus of SRP68 mediated the binding to SRP72. The SRP68-SRP72 interaction remained stable at elevated salt concentrations and engaged approximately 150 amino acids from the N-terminal region of SRP72. This portion of SRP72 was located within a predicted tandem array of four tetratricopeptide (TPR)-like motifs suggested to form a superhelical structure with a groove to accommodate the C-terminal region of SRP68.
Collapse
Affiliation(s)
- Elena Iakhiaeva
- Department of Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas 75708-3154, USA
| | | | | | | |
Collapse
|
8
|
Römisch K, Miller FW, Dobberstein B, High S. Human autoantibodies against the 54 kDa protein of the signal recognition particle block function at multiple stages. Arthritis Res Ther 2006; 8:R39. [PMID: 16469117 PMCID: PMC1526608 DOI: 10.1186/ar1895] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 12/12/2005] [Accepted: 01/03/2006] [Indexed: 11/10/2022] Open
Abstract
The 54 kDa subunit of the signal recognition particle (SRP54) binds to the signal sequences of nascent secretory and membrane proteins and it contributes to the targeting of these precursors to the membrane of the endoplasmic reticulum (ER). At the ER membrane, the binding of the signal recognition particle (SRP) to its receptor triggers the release of SRP54 from its bound signal sequence and the nascent polypeptide is transferred to the Sec61 translocon for insertion into, or translocation across, the ER membrane. In the current article, we have characterized the specificity of anti-SRP54 autoantibodies, which are highly characteristic of polymyositis patients, and investigated the effect of these autoantibodies on the SRP function in vitro. We found that the anti-SRP54 autoantibodies had a pronounced and specific inhibitory effect upon the translocation of the secretory protein preprolactin when analysed using a cell-free system. Our mapping studies showed that the anti-SRP54 autoantibodies bind to the amino-terminal SRP54 N-domain and to the central SRP54 G-domain, but do not bind to the carboxy-terminal M-domain that is known to bind ER signal sequences. Nevertheless, anti-SRP54 autoantibodies interfere with signal-sequence binding to SRP54, most probably by steric hindrance. When the effect of anti-SRP autoantibodies on protein targeting the ER membrane was further investigated, we found that the autoantibodies prevent the SRP receptor-mediated release of ER signal sequences from the SRP54 subunit. This observation supports a model where the binding of the homologous GTPase domains of SRP54 and the alpha-subunit of the SRP receptor to each other regulates the release of ER signal sequences from the SRP54 M-domain.
Collapse
Affiliation(s)
- Karin Römisch
- University of Cambridge, Cambridge Institute for Medical Research and Department of Clinical Biochemistry, Cambridge, UK
| | - Frederick W Miller
- Environmental Autoimmunity Group, National Institute of Environmental Health Sciences, National Institutes of Health, HHS, Bethesda, Maryland, USA
| | - Bernhard Dobberstein
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Stephen High
- Faculty of Life Sciences, University of Manchester, UK
| |
Collapse
|
9
|
Yin J, Yang CH, Zwieb C. Two strategically placed base pairs in helix 8 of mammalian signal recognition particle RNA are crucial for the SPR19-dependent binding of protein SRP54. RNA (NEW YORK, N.Y.) 2004; 10:574-580. [PMID: 15037766 PMCID: PMC1370547 DOI: 10.1261/rna.5232404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Accepted: 01/07/2004] [Indexed: 05/24/2023]
Abstract
Signal recognition particle (SRP) guides secretory proteins to biological membranes in all organisms. Assembly of the large domain of mammalian SRP requires binding of SRP19 prior to the binding of protein SRP54 to SRP RNA. The crystal structure of the ternary complex reveals the parallel arrangement of RNA helices 6 and 8, a bridging of the helices via a hydrogen bonded A149-A201 pair and protein SRP19, and two A minor motifs between the asymmetric loop of helix 8 (A213 and A214) and helix 6. We investigated which residues in helix 8 are responsible for the SRP19-dependent binding of SRP54 by taking advantage of the finding that binding of human SRP54 to Methanococcus jannaschii SRP RNA is independent of SRP19. Chimeric human/M. jannaschii SRP RNA molecules were synthesized containing predominantly human SRP RNA but possessing M. jannaschii SRP RNA-derived substitutions. Activities of the chimeric RNAs were measured with respect to protein SRP19 and the methionine-rich RNA-binding domain of protein SRP54 (SRP54M). Changing A213 and A214 to a uridine has no effect on the SRP19-dependent binding of SRP54M. Instead, the two base pairs C189-G210 and C190-G209, positioned between the conserved binding site of SRP54 and the asymmetric loop, are critical for conveying SRP19 dependency. Furthermore, the nucleotide composition of five base pairs surrounding the asymmetric loop affects binding of SRP54M significantly. These results demonstrate that subtle, and not easily perceived, structural differences are of crucial importance in the assembly of mammalian SRP.
Collapse
Affiliation(s)
- Jiaming Yin
- Department of Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, Texas 75708-3154, USA
| | | | | |
Collapse
|
10
|
Bhuiyan SH, Gowda K, Hotokezaka H, Zwieb C. Assembly of archaeal signal recognition particle from recombinant components. Nucleic Acids Res 2000; 28:1365-73. [PMID: 10684931 PMCID: PMC111052 DOI: 10.1093/nar/28.6.1365] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Signal recognition particle (SRP) takes part in protein targeting and secretion in all organisms. Searches for components of archaeal SRP in primary databases and completed genomes indicated that archaea possess only homologs of SRP RNA, and proteins SRP19 and SRP54. A recombinant SRP was assembled from cloned, expressed and purified components of the hyperthermophilic archaeon Archaeoglobus fulgidus. Recombinant Af-SRP54 associated with the signal peptide of bovine pre-prolactin translated in vitro. As in mammalian SRP, Af-SRP54 binding to Af-SRP RNA required protein Af-SRP19, although notable amounts bound in absence of Af-SRP19. Archaeoglobus fulgidus SRP proteins also bound to full-length SRP RNA of the archaeon Methanococcus jannaschii, to eukaryotic human SRP RNA, and to truncated versions which corresponded to the large domain of SRP. Dependence on SRP19 was most pronounced with components from the same species. Reconstitutions with heterologous components revealed a significant potential of human SRP proteins to bind to archaeal SRP RNAs. Surprisingly, M.jannaschii SRP RNA bound to human SRP54M quantitatively in the absence of SRP19. This is the first report of reconstitution of an archaeal SRP from recombinantly expressed purified components. The results highlight structural and functional conservation of SRP assembly between archaea and eucarya.
Collapse
Affiliation(s)
- S H Bhuiyan
- Department of Molecular Biology, The University of Texas Health Science Center at Tyler, TX 75710, USA
| | | | | | | |
Collapse
|
11
|
Politz JC, Yarovoi S, Kilroy SM, Gowda K, Zwieb C, Pederson T. Signal recognition particle components in the nucleolus. Proc Natl Acad Sci U S A 2000; 97:55-60. [PMID: 10618370 PMCID: PMC26615 DOI: 10.1073/pnas.97.1.55] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The signal recognition particle (SRP) is a ribonucleoprotein composed of an Alu domain and an S domain. The S domain contains unique sequence SRP RNA and four SRP proteins: SRP19, SRP54, SRP68, and SRP72. SRP interacts with ribosomes to bring translating membrane and secreted proteins to the endoplasmic reticulum (ER) for proper processing. Additionally, SRP RNA is a member of a family of small nonribosomal RNAs found recently in the nucleolus, suggesting that the nucleolus is more plurifunctional than previously realized. It was therefore of interest to determine whether other SRP components localize to this intranuclear site. In transfected rat fibroblasts, green fluorescent protein fusions of SRP19, SRP68, and SRP72 localized to the nucleolus, as well as to the cytoplasm, as expected. SRP68 also accumulated in the ER, consistent with its affinity for the ER-bound SRP receptor. SRP54 was detected in the cytoplasm as a green fluorescent protein fusion and in immunofluorescence studies, but was not detected in the nucleolus. In situ hybridization experiments also revealed endogenous SRP RNA in the nucleolus. These results demonstrate that SRP RNA and three SRP proteins visit the nucleolus, suggesting that partial SRP assembly, or another unidentified activity of the SRP components, occurs at the nucleolus. SRP54 apparently interacts with nascent SRP beyond the nucleolus, consistent with in vitro reconstitution experiments showing that SRP19 must bind to SRP RNA before SRP54 binds. Our findings support the notion that the nucleolus is the site of assembly and/or interaction between the family of ribonucleoproteins involved in protein synthesis, in addition to ribosomes themselves.
Collapse
Affiliation(s)
- J C Politz
- Department of Biochemistry, University of Massachusetts Medical School, 377 Plantation Street, Suite 337, Worcester, MA 01605, USA
| | | | | | | | | | | |
Collapse
|
12
|
Clemons WM, Gowda K, Black SD, Zwieb C, Ramakrishnan V. Crystal structure of the conserved subdomain of human protein SRP54M at 2.1 A resolution: evidence for the mechanism of signal peptide binding. J Mol Biol 1999; 292:697-705. [PMID: 10497032 DOI: 10.1006/jmbi.1999.3090] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Protein SRP54 is an integral part of the mammalian signal recognition particle (SRP), a cytosolic ribonucleoprotein complex which associates with ribosomes and serves to recognize, bind, and transport proteins destined for the membrane or secretion. The methionine-rich M-domain of protein SRP54 (SRP54M) binds the SRP RNA and the signal peptide as the nascent protein emerges from the ribosome. A focal point of this critical cellular function is the detailed understanding of how different hydrophobic signal peptides are recognized efficiently and transported specifically, despite considerable variation in sequence. We have solved the crystal structure of a conserved functional subdomain of the human SRP54 protein (hSRP54m) at 2.1 A resolution showing a predominantly alpha helical protein with a large fraction of the structure available for binding. RNA binding is predicted to occur in the vicinity of helices 4 to 6. The N-terminal helix extends significantly from the core of the structure into a large but constricted hydrophobic groove of an adjacent molecule, thus revealing molecular details of possible interactions between alpha helical signal peptides and human SRP54.
Collapse
Affiliation(s)
- W M Clemons
- Department of Biochemistry, The University of Utah, School of Medicine, 50 North Medical Drive, Salt Lake City, UT 84132, USA
| | | | | | | | | |
Collapse
|
13
|
Gowda K, Clemons WM, Zwieb C, Black SD. Expression, purification, and crystallography of the conserved methionine-rich domain of human signal recognition particle 54 kDa protein. Protein Sci 1999; 8:1144-51. [PMID: 10338025 PMCID: PMC2144335 DOI: 10.1110/ps.8.5.1144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Protein SRP54 is an essential component of eukaryotic signal recognition particle (SRP). The methionine-rich M-domain (SRP54M or 54M) interacts with the SRP RNA and is also involved in the binding to signal peptides of secretory proteins during their targeting to cellular membranes. To gain insight into the molecular details of SRP-mediated protein targeting, we studied the human 54M polypeptide. The recombinant human protein was expressed successfully in Escherichia coli and was purified to homogeneity. Our studies determined the sites that were susceptible to limited proteolysis, with the goal to design smaller functional mutant derivatives that lacked nonessential amino acid residues from both termini. Of the four polypeptides produced by V8 protease or chymotrypsin, 54MM-2 was the shortest (120 residues; Mr = 13,584.8), but still contained the conserved amino acids suggested to associate with the signal peptide or the SRP RNA. 54MM-2 was cloned, expressed, purified to homogeneity, and was shown to bind human SRP RNA in the presence of protein SRP19, indicating that it was functional. Highly reproducible conditions for the crystallization of 54MM-2 were established. Examination of the crystals by X-ray diffraction showed an orthorhombic unit cell of dimensions a = 29.127 A, b = 63.693 A, and c = 129.601 A, in space group P2(1)2(1)2(1), with reflections extending to at least 2.0 A.
Collapse
Affiliation(s)
- K Gowda
- Department of Molecular Biology, The University of Texas Health Science Center at Tyler, 75710, USA
| | | | | | | |
Collapse
|