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J. Bacteriol., 10 1996, 6001-6005, Vol 178, No. 20
T Murray, DL Popham and P Setlow
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.
Copyright © 1996, American Society for Microbiology
Identification and characterization of pbpC, the gene encoding Bacillus subtilis penicillin-binding protein 3
Department of Biochemistry, University of Connecticut Health Center, Farmington 06030, USA.
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