Isolation and characterization of dcw cluster from Streptomyces collinus producing kirromycin

Global features of gene expression on the proteome and transcriptome levels in S. coelicolor during germination

Streptomycetes have been studied mostly as producers of secondary metabolites, while the transition from dormant spores to an exponentially growing culture has largely been ignored. Here, we focus on a comparative analysis of fluorescently and radioactively labeled proteome and microarray acquired transcriptome expressed during the germination of Streptomyces coelicolor. The time-dynamics is considered, starting from dormant spores through 5.5 hours of growth with 13 time points. Time series of the gene expressions were analyzed using correlation, principal components analysis and an analysis of coding genes utilization. Principal component analysis was used to identify principal kinetic trends in gene expression and the corresponding genes driving S. coelicolor germination. In contrast with the correlation analysis, global trends in the gene/protein expression reflected by the first principal components showed that the prominent patterns in both the protein and the mRNA domains are surprisingly well correlated. Analysis of the number of expressed genes identified functional groups activated during different time intervals of the germination.

Bacterial cell division protein FtsZ is stable against degradation by AAA family protease FtsH in Escherichia coli cells

We have found that FtsH protease of Escherichia coli could degrade E. coli cell division protein FtsZ in an ATP- and Zn(2+)-dependent manner in vitro and that the degradation did not show specificity for the N-terminus or C-terminus of FtsZ, like in the case of degradation of its conventional substrate sigma(32) protein. In continuation of these observations, in the present study, we examined whether FtsH would affect the stability and turnover of FtsZ in vivo. We found that FtsZ levels were not elevated in E. coli AR754 (ftsH1 ts) cells at nonpermissive temperature as compared to the levels in an FtsH-active isogenic AR753 strain. Neither did FtsH degrade ectopically expressed FtsZ in AR754 strain nor did ectopic expression of FtsH reduced FtsZ levels in E. coli AR5090 ftsH null strain (ftsH::kan, sfhC21). Pulse chase experiments in AR754 and AR5090 strains showed that there were no compensatory changes in FtsZ turnover, in case FtsZ degradation had occurred. Even under cell division arrested conditions, wherein FtsZ was not required, FtsH protease did not degrade unutilized FtsZ. These experiments demonstrate that either FtsH protease may not have a role in regulating the levels of FtsZ in vivo under the conditions tested or that some cellular component(s) might be stabilising FtsZ against FtsH protease.

Transcriptional analysis of the principal cell division gene, ftsZ, of Mycobacterium tuberculosis

Multiple promoters drive the expression of the principal cell division gene, ftsZ, in bacterial systems. Primer extension analysis of total RNA from Mycobacterium tuberculosis and a Mycobacterium smegmatis transformant containing 1.117 kb of the upstream region of M. tuberculosis ftsZ and promoter fusion studies identified six ftsZ transcripts and their promoters in the ftsQ open reading frame and ftsQ-ftsZ intergenic region. The presence of multiple promoters reflects the requirement to maintain a high basal level of, or to differentially regulate, FtsZ expression during different growth conditions of the pathogen in vivo.

Identification and semi-quantitative analysis of Mycobacterium tuberculosis H37Rv ftsZ gene-specific promoter activity-containing regions

The cytokinetic protein FtsZ plays a pivotal role in regulation of cell division in bacteria. Multiple promoters regulate transcription of the ftsZ gene in Escherichia coli, Streptomyces and Bacillus species. In order to identify promoter activity-containing regions of the ftsZ gene of Mycobacterium tuberculosis H37Rv (MtftsZ) in vivo, different regions upstream of MtftsZ, namely, the ftsQ-ftsZ intergenic region, the ftsQ open reading frame (ORF), and different regions of ftsQ ORF, were analyzed in a gfp reporter plasmid in Mycobacterium smegmatis mc(2)155 cells. Flow cytometric analysis of mid-logarithmic M. smegmatis mc(2)155 cells containing these transcription fusion constructs revealed GFP expression in the cells harboring the ftsQ-ftsZ intergenic region (172 bp), the entire ftsQ ORF (945 bp), and 5' 467-bp and 3' 217-bp regions of ftsQ ORF. RT-PCR analyses on RNA from M. smegmatis mc(2)155 cells, transformed with the entire ftsQ ORF-ftsQ-ftsZ intergenic region-containing construct, as well as on RNA from M. tuberculosis, confirmed that the regions identified indeed elicit promoter activity. Semi-quantitative RT-PCR analyses of gfp transcripts driven by cloned MtftsZ promoter regions in M. smegmatis cells showed threefold higher promoter activity from ftsQ ORF than from the ftsQ-ftsZ intergenic region. Expression from the individual 5' and 3' regions of ftsQ ORF was almost equivalent to that from the ftsQ-ftsZ intergenic region. RT-PCR analyses on RNA from M. tuberculosis quantitatively confirmed these promoter activities. Thus, at least three independent regions in the immediate upstream sequence of MtftsZ contain promoter activity, with the major contribution coming from ftsQ ORF.

The tubulin ancestor, FtsZ, draughtsman, designer and driving force for bacterial cytokinesis

We discuss in this review the regulation of synthesis and action of FtsZ, its structure in relation to tubulin and microtubules, and the mechanism of polymerization and disassembly (contraction) of FtsZ rings from a specific nucleation site (NS) at mid cell. These topics are considered in the light of recent immunocytological studies, high resolution structures of some division proteins and results indicating how bacteria may measure their mid cell point.

Differential regulation of ftsZ transcription during septation of Streptomyces griseus

Streptomyces has been known to form two types of septa. The data in this research demonstrated that Streptomyces griseus forms another type of septum near the base of sporogenic hyphae (basal septum). To understand the regulation of the septation machinery in S. griseus, we investigated the expression of the ftsZ gene. S1 nuclease protection assays revealed that four ftsZ transcripts were differentially expressed during morphological differentiation. The vegetative transcript (emanating from P(veg)) is present at a moderate level during vegetative growth, but is switched off within the first 2 h of sporulation. Two sporulation-specific transcripts predominantly accumulated, and the levels increased by approximately fivefold together shortly before sporulation septa begin to form. Consistently, the sporulation-specific transcripts were expressed much earlier and more abundantly in a group of nonsporulating mutants that form their sporulation septa prematurely. Promoter-probe studies with two different reporter systems confirmed the activities of the putative promoters identified from the 5' end point of the transcripts. The levels and expression timing of promoter activities were consistent with the results of nuclease protection assays. The aseptate phenotype of the P(spo) mutant indicated that the increased transcription from P(spo) is required for sporulation septation, but not for vegetative or basal septum formation.

Generation of a non-sporulating strain of Streptomyces coelicolor A3(2) by the manipulation of a developmentally controlled ftsZ promoter

The differentiation of Streptomyces aerial hyphae into chains of unigenomic spores occurs through the synchronous formation of multiple FtsZ rings, leading to sporulation septa. We show here that developmental control of ftsZ transcription is required for sporulation in Streptomyces coelicolor A3(2). Three putative ftsZ promoters were detected in the ftsQ-ftsZ intergenic region. In addition, some readthrough from upstream promoter(s) contributed to ftsZ transcription. S1 nuclease protection assays and transcriptional fusions of the ftsZ promoter region to the egfp gene (for green fluorescent protein) provided evidence that ftsZ2p is a developmentally controlled promoter that is specifically upregulated in sporulating aerial hyphae. This upregulation required all the six early regulatory sporulation genes that were tested: whiA, B, G, H, I and J. The DNA sequence of the promoter indicated that it is not part of the developmental regulon that is controlled by the RNA polymerase sigma factor sigma(WhiG). A strain in which the ftsZ2p promoter was inactivated grew normally during vegetative growth and formed aerial mycelium, but was deficient in sporulation septation. Thus, ftsZ2p was dispensable for vegetative growth, but was required for the strain to make sufficient FtsZ to support developmentally controlled multiple cell divisions in aerial hyphae.