Posttranslational processing of the xylanase Xys1L from Streptomyces halstedii JM8 is carried out by secreted serine proteases.
The xylanase Xys1L from Streptomyces halstedii JM8 is known to be processed extracellularly, to produce a protein of 33.7 kDa, Xys1S, that retains catalytic activity but not its cellulose-binding capacity. This paper demonstrates that at least five serine proteases isolated from Streptomyces spp. have the ability to process the xylanase Xys1L. The genes of two of these extracellular serine proteases, denominated SpB and SpC, were cloned from Streptomyces lividans 66 (a strain commonly used as a host for protein secretion), sequenced, and overexpressed in S. lividans; both purified proteases were able to process Xys1L in vitro. Three other previously reported purified Streptomyces serine proteases, SAM-P20, SAM-P26 and SAM-P45, also processed Xys1L in vitro. The involvement of serine proteases in xylanase processing-degradation in vivo was demonstrated by co-expression of the xylanase gene (xysA) and the gene encoding the serine protease inhibitor (SLPI) from S. lividans. Co-expression prevented processing and degradation of Xys1L and resulted in a threefold increase in the xylanase activity present in the culture supernatant. SpB and SpC also have the capacity to process other secreted proteins such as p40, a cellulose-binding protein from S. halstedii JM8, but do not have any clear effect on other secreted proteins such as amylase (Amy) from Streptomyces griseus and xylanase Xyl30 from Streptomyces avermitilis.
Fernández-Abalos
José M
JM
Instituto de Microbiología Bioquímica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
Reviejo
Verónica
V
Instituto de Microbiología Bioquímica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
Díaz
Margarita
M
Instituto de Microbiología Bioquímica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
Rodríguez
Sonia
S
Instituto de Microbiología Bioquímica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
Leal
Fernando
F
Instituto de Microbiología Bioquímica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
Santamaría
Ramón I
RI
Instituto de Microbiología Bioquímica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D015870:Gene Expression; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics; D014995:Xylosidases / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015842:Serine Proteinase Inhibitors; C116416:SAM-P26 serine protease, Streptomyces; D014995:Xylosidases; C107879:Xys1 protein, Streptomyces halstedii; D012697:Serine Endopeptidases