Expression of the Staphylococcus aureus surface proteins HtrA1 and HtrA2 in Lactococcus lactis.
Staphylococcus aureus encodes two HtrA-like serine surface proteases, called HtrA1 and HtrA2. The roles of these HtrA homologs were distinguished by expression studies in a heterologous host, Lactococcus lactis, whose single extracellular protease, HtrA(Ll), was absent. HtrA(Ll) is involved in stress resistance, and processing and/or degradation of extracellular proteins. Controlled expression of staphylococcal htrA1 and htrA2 was achieved in L. lactis strain NZ9000 DeltahtrA, as confirmed with anti-HtrA1 and anti-HtrA2 specific antibodies. HtrA1 fully restored thermo-resistance to the htrA-defective L. lactis strain, despite a poor capacity to degrade abnormal or truncated proteins. We therefore propose that activities of HtrA1 other than proteolysis may be sufficient for high-temperature growth complementation. HtrA2 is 36% identical to HtrA(Ll), and was highly expressed in L. lactis; nevertheless, it displayed nearly no detectable activities. The poor proteolytic activities of staphylococcal HtrA proteins in L. lactis may reflect a requirement for S. aureus-specific co-factors.
Unité de Recherches Laitières et Génétique Appliquée, INRA, Domaine de Vilvert, 78352 Jouy en Josas cedex, France. rigoulay@jouy.inra.fr
Candice
C
Rigoulay
Isabelle
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Poquet
Søren M
SM
Madsen
Alexandra
A
Gruss
D000595:Amino Acid Sequence; D000907:Antibodies, Bacterial / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002455:Cell Division; D017353:Gene Deletion; D015870:Gene Expression; D013294:Lactococcus lactis / Q000166:cytology / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013211:Staphylococcus aureus / Q000201:enzymology*; D013696:Temperature
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins; D012697:Serine Endopeptidases