Dataset Information

Identification and characterization of pbpC, the gene encoding Bacillus subtilis penicillin-binding protein 3.

ABSTRACT: Penicillin-binding proteins (PBPs) are enzymes involved in the synthesis of peptidoglycan structures in Bacillus subtilis such as the vegetative cell wall and the spore cortex. The B. subtilis sequencing project has identified a gene (orf16, EMBL accession number D38161) which exhibits significant sequence similarity to genes encoding class B high-molecular-weight PBPs. We have found that orf16 encodes PBP3 and have renamed this locus pbpC. Transcriptional fusions to lacZ were used to demonstrate that pbpC is transcribed primarily during log-phase growth, with lower amounts expressed during sporulation. During spore germination and outgrowth, pbpC expression resumes coincident with an increase in the optical density of the culture. The major promoter for pbpC is located just upstream of the gene; a low level of expression during sporulation appears to originate from much further upstream. Loss of PBP3 does not produce any detectable change in phenotype with respect to cell morphology, growth, sporulation, spore heat resistance, or spore germination and outgrowth. This was also true when the pbpC mutation was combined with mutations affecting other PBP-encoding genes to produce double mutants. These findings are consistent with previous evidence that many PBPs of B. subtilis have redundant functions within the cell.

SUBMITTER: Murray T

PROVIDER: S-EPMC178458 | biostudies-literature | 1996 Oct

REPOSITORIES: biostudies-literature

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Identification and characterization of pbpC, the gene encoding Bacillus subtilis penicillin-binding protein 3.

Murray T T Popham D L DL Setlow P P

Journal of bacteriology 19961001 20

Penicillin-binding proteins (PBPs) are enzymes involved in the synthesis of peptidoglycan structures in Bacillus subtilis such as the vegetative cell wall and the spore cortex. The B. subtilis sequencing project has identified a gene (orf16, EMBL accession number D38161) which exhibits significant sequence similarity to genes encoding class B high-molecular-weight PBPs. We have found that orf16 encodes PBP3 and have renamed this locus pbpC. Transcriptional fusions to lacZ were used to demonstrat ...[more]

PMID: 8830698

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Project description:Penicillin-binding proteins (PBPs) play critical roles in cell wall construction, cell shape maintenance, and bacterial replication. Bacteria maintain a diversity of PBPs, indicating that despite their apparent functional redundancy, there is differentiation across the PBP family. Apparently-redundant proteins can be important for enabling an organism to cope with environmental stressors. In this study, we evaluated the consequence of environmental pH on PBP enzymatic activity in Bacillus subtilis. Our data show that a subset of PBPs in B. subtilis change activity levels during alkaline shock and that one PBP isoform is rapidly modified to generate a smaller protein (i.e., PBP1a to PBP1b). Our results indicate that a subset of the PBPs are favored for growth under alkaline conditions, while others are readily dispensable. Indeed, we found that this phenomenon could also be observed in Streptococcus pneumoniae, implying that it may be generalizable across additional bacterial species and further emphasizing the evolutionary benefit of maintaining many, seemingly-redundant periplasmic enzymes.IMPORTANCEMicrobes adapt to ever-changing environments and thrive over a vast range of conditions. While bacterial genomes are relatively small, significant portions encode for "redundant" functions. Apparent redundancy is especially pervasive in bacterial proteins that reside outside of the inner membrane. While conditions within the cytoplasm are carefully controlled, those of the periplasmic space are largely determined by the cell's exterior environment. As a result, proteins within this environmentally exposed region must be capable of functioning under a vast array of conditions, and/or there must be several similar proteins that have evolved to function under a variety of conditions. This study examines the activity of a class of enzymes that is essential in cell wall construction to determine if individual proteins might be adapted for activity under particular growth conditions. Our results indicate that a subset of these proteins are preferred for growth under alkaline conditions, while others are readily dispensable.

Dataset Information

Identification and characterization of pbpC, the gene encoding Bacillus subtilis penicillin-binding protein 3.

Publications

Identification and characterization of pbpC, the gene encoding Bacillus subtilis penicillin-binding protein 3.

Similar Datasets

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