The Bacillus subtilis yabQ gene is essential for formation of the spore cortex.
An extensive screening for transcripts with probes specific for the genes in a 108 kb region from rrnO to spo0H of the Bacillus subtilis chromosome led to identification of an operon, yabP--yabQ--divIC--yabR, the expression of which was initiated at the second hour of sporulation and in a sigma(E)-dependent manner. Among three y genes in the operon, deletion of the yabQ gene, which is predicted to encode a protein product of 468 residues with five membrane-spanning domains, resulted in a large decrease in numbers of chloroform-, lysozyme- and heat-resistant spores, compared to findings with the wild-type strain. Electron microscopy revealed that development of the spore cortex was blocked in the yabQ mutant. In addition, although the spore coat was visible, the inner coat layer of the mutant seemed partially detached from the outer coat. In sporangia of the strains harbouring an in-frame fusion of the green fluorescent protein gene to yabQ, fluorescence was detected around the forespore. This localization did not depend on SpoIVA or on CotE functions, both of which determine proper localization of coat proteins and cortex formation. The yabQ deletion did not affect expression of genes involved in cortex synthesis. These results suggest that the YabQ protein localizes in the membrane of the forespore and plays an important role in cortex formation.
Department of Cell Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan1.
Kei
K
Asai
Faculty of Pharmaceutical Sciences, Setsunan University, 45-1, Nagaotoge, Hirakata, Osaka 573-0101, Japan2.
Hiromu
H
Takamatsu
Department of Cell Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan1.
Megumi
M
Iwano
Faculty of Pharmaceutical Sciences, Setsunan University, 45-1, Nagaotoge, Hirakata, Osaka 573-0101, Japan2.
Takeko
T
Kodama
Faculty of Pharmaceutical Sciences, Setsunan University, 45-1, Nagaotoge, Hirakata, Osaka 573-0101, Japan2.
Kazuhito
K
Watabe
Department of Cell Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan1.
Naotake
N
Ogasawara
D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015152:Blotting, Northern; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D016297:Mutagenesis, Site-Directed; D009876:Operon; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D013171:Spores, Bacterial / Q000235:genetics* / Q000648:ultrastructure
D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; C110609:DivIC protein, Bacillus subtilis; D008164:Luminescent Proteins; D008565:Membrane Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D049452:Green Fluorescent Proteins