To analyse the proteome of Bacillus subtilis extracellular proteins, extracellular protein samples were prepared from culture media (minimal medium containing 04 % glucose) of parental B. subtilis 168, a secA-temperature sensitive mutant and an ffh conditional mutant, and examined by twodimensional gel electrophoresis. Approximately 100 to 110 spots were visualized in a gel of B. subtilis 168 extracellular proteins. Over 90 % and 80 % of these disappeared in the absence of SecA and Ffh, respectively. Thirty-eight obvious spots on the gel of the B. subtilis 168 preparation were selected and compared with spots obtained under SecA-or Ffh-deficient conditions. The appearance of 36 of these 38 spots depended on SecA and Ffh. Nineteen additional extracellular proteins were detected in cultures maintained in cellobiose, maltose and soluble starch. Among 23 proteins of which the Nterminal amino acid sequences were determined, 17 were extracellular proteins having signal peptides in their precursor form. Two membrane proteins, YfnI and YflE, were cleaved behind 226 Ala-Tyr-Ala 228 and 213 Ala-LeuAla 215 , respectively, and of which products seemed to be liberated into the culture medium. The production of YfnI and YflE were also dependent on SecA and Ffh. These results indicate that most extracellular proteins target to and translocate across the cytoplasmic membrane by co-operation between the signal-recognition particle and Sec protein-secretion pathways. In contrast, a spot for Hag appeared independent from SecA and Ffh. Intracellular proteins Gap, SodA and KatA were identified in the extracellular protein samples. On the basis of these results and computer searches, it was predicted that B. subtilis produces 150 to 180 proteins extracellularly.
Low-field-strength MR imaging depicted periprosthetic tissue signal intensity that was significantly associated with radiographic, surgical, and pathologic findings.
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