Depletion of Bacillus subtilis histone-like protein, HBsu, causes defective protein translocation and induces upregulation of small cytoplasmic RNA.
Small cytoplasmic RNA (scRNA) is a metabolically stable homologue of mammalian SRP RNA that contains an Alu-like domain. The Bacillus subtilis histone-like protein HBsu can bind this domain. We demonstrate here that repressing the level of HBsu results in slow growth and the accumulation of precursor of beta-lactamase fusion proteins having the signal sequence of alkaline protease, penicillin binding protein 5* (PBP5*) or CGTase. The degree of the translocation defect varied among the various signal sequences tested. A pulse-chase experiment showed that processing the alpha-amylase signal sequence is significantly inhibited in HBsu-depleted cells. Northern blot analysis indicated that repressing the HBsu gene induces scRNA upregulation, indicating that the defective translocation of presecretory proteins is not due to a reduced scRNA level. The data presented here suggest that HBsu plays a pivotal role in SRP function rather than simply stabilizing the other SRP components such as scRNA.
Yamazaki
T
T
Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki, 305, Japan.
Yahagi
S
S
Nakamura
K
K
Yamane
K
K
D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins; D001692:Biological Transport; D004268:DNA-Binding Proteins / Q000378:metabolism*; D012313:RNA / Q000378:metabolism*; D020733:RNA, Small Cytoplasmic; D015854:Up-Regulation
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C075779:Hbsu protein, bacteria; D020733:RNA, Small Cytoplasmic; D012313:RNA