title: Surface plasmon resonance-based interaction studies reveal competition of Streptomyces lividans type I signal peptidases for binding preproteins.
abstract: Type I signal peptidases (SPases) are responsible for the cleavage of signal peptides from secretory proteins. Streptomyces lividans contains four different SPases, denoted SipW, SipX, SipY and SipZ, having at least some differences in their substrate specificity. In this report in vitro preprotein binding/processing and protein secretion in single SPase mutants was determined to gain more insight into the substrate specificity of the different SPases and the underlying molecular basis. Results indicated that preproteins do not preferentially bind to a particular SPase, suggesting SPase competition for binding preproteins. This observation, together with the fact that each SPase could process each preprotein tested with a similar efficiency in an in vitro assay, suggested that there is no real specificity in substrate binding and processing, and that they are all actively involved in preprotein processing in vivo. Although this seems to be the case for some proteins tested, high-level secretion of others was clearly dependent on only one particular SPase demonstrating clear differences in substrate preference at the in vivo processing level. Hence, these results strongly suggest that there are additional factors other than the cleavage requirements of the enzymes that strongly affect the substrate preference of SPases in vivo.
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Nick
authors.initials: N
authors.lastname: Geukens
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Smitha
authors.initials: S
authors.lastname: Rao C V
authors.affiliation: Department of Microbial Biotechnology, Centro Nacional de Biotecnologia, Campus de la Universidad Autonoma, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Rafael P
authors.initials: RP
authors.lastname: Mellado
authors.affiliation: IMEC, MCP-ART, Kapeldreef 75, B-3001 Leuven, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Frederix
authors.affiliation: IMEC, MCP-ART, Kapeldreef 75, B-3001 Leuven, Belgium.
authors.forename: Gunter
authors.initials: G
authors.lastname: Reekmans
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Sophie
authors.initials: S
authors.lastname: De Keersmaeker
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Kristof
authors.initials: K
authors.lastname: Vrancken
authors.affiliation: IMEC, MCP-ART, Kapeldreef 75, B-3001 Leuven, Belgium.
authors.forename: Kristien
authors.initials: K
authors.lastname: Bonroy
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Lieve
authors.initials: L
authors.lastname: Van Mellaert
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Lammertyn
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Jozef
authors.initials: J
authors.lastname: Anné
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D015153:Blotting, Western; D003470:Culture Media / Q000737:chemistry; D017353:Gene Deletion; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism*; D021382:Protein Sorting Signals; D021381:Protein Transport; D012697:Serine Endopeptidases / Q000378:metabolism*; D048170:Streptomyces lividans / Q000201:enzymology*; D013379:Substrate Specificity; D020349:Surface Plasmon Resonance
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D008565:Membrane Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; D012697:Serine Endopeptidases; C026515:type I signal peptidase