Effect of protease mutations on the production of xylanases in Streptomyces lividans.
Three protease mutants--7 (tap-), 12 (tap-, ssp-), and 17 (multiple mutations)--of Streptomyces lividans were tested for their influence on protein secretion. Streptomyces lividans grown in xylan secretes 3 xylanases (A, B, and C). Xylanases A (XlnA) and B (XlnB) are secreted by the Sec pathway, whereas xylanase C (XlnC) is secreted by the Tat pathway. The production of XlnA and XlnC was affected in the mutants, suggesting that the mutations interfered with both Sec- and Tat-secretion systems. However, the processing rate for the Sec and Tat precursor was similar to the wild-type strain, indicating that the mutations had no direct effect on secretion. Streptomyces lividans naturally produced 2 forms of XlnB: XlnB1, which contains the catalytic and the xylan-binding domains, and XlnB2, which contains the catalytic domain only. There was no change from the wild-type strain in the ratio of XlnB1/XlnB2 produced by the mutants, indicating that these proteases are not involved in this process. Although XlnA1, partially truncated in its xylan-binding domain, was rapidly degraded to its catalytic domain (XlnA2) in the wild-type strain, the rate of conversion was reduced in the 3 mutants, indicating that the proteases participated to some extent in this proteolytic process.
INRS - Institut Armand-Frappier, Université du Québec, 531 boulevard des Prairies, Laval, QC H7V 1B7, Canada.
Eliana
E
Arias
Haiming
H
Li
Rolf
R
Morosoli
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D009154:Mutation; D010447:Peptide Hydrolases / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D048170:Streptomyces lividans / Q000201:enzymology / Q000235:genetics*
D001426:Bacterial Proteins; D007527:Isoenzymes; D011994:Recombinant Proteins; D043364:Endo-1,4-beta Xylanases; D010447:Peptide Hydrolases