title: SlpE is a calcium-dependent cytotoxic metalloprotease associated with clinical isolates of Serratia marcescens.
abstract: Serralysin-like proteases are found in a wide variety of bacteria. These metalloproteases are frequently implicated in virulence and are members of the widely conserved RTX-toxin family. We identified a serralysin-like protease in the genome of a clinical isolate of Serratia marcescens that is highly similar to the canonical serralysin protein, PrtS. This gene was named serralysin-like protease E, SlpE, and was found in the majority (67%) of tested clinical isolates, but was absent from most tested non-clinical isolates including the insect pathogen and reference S. marcescens strain Db11. Purified recombinant SlpE exhibited calcium-dependent protease activity similar to metalloproteases PrtS and SlpB. Induction of slpE in the low-protease-producing S. marcescens strain PIC3611 highly elevated extracellular protease activity, and extracellular secretion required the lipD type 1 secretion system gene. Transcription of slpE was highly reduced in an eepR transcription factor mutant. Mutation of the slpE gene in a highly proteolytic clinical isolate reduced its protease activity, and evidence suggests that SlpE confers cytotoxicity of S. marcescens to the A549 airway carcinoma cell line. Together, these data reveal SlpE to be an EepR-regulated cytotoxic metalloprotease associated with clinical isolates of an important opportunistic pathogen.
authors.affiliation: Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Stella
authors.affiliation: Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Jake D
authors.initials: JD
authors.lastname: Callaghan
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Brothers
authors.affiliation: Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Regis P
authors.initials: RP
authors.lastname: Kowalski
authors.affiliation: Department of Biology, Olin College, Needham, MA 02492, USA.
authors.forename: Jean J
authors.initials: JJ
authors.lastname: Huang
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Patrick H
authors.initials: PH
authors.lastname: Thibodeau
authors.affiliation: Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA 15219, USA. Electronic address: shanksrm@upmc.edu.
authors.forename: Robert M Q
authors.initials: RMQ
authors.lastname: Shanks
mesh_terms: D000072283:A549 Cells; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D004847:Epithelial Cells; D016680:Genome, Bacterial; D006801:Humans; D008666:Metalloendopeptidases / Q000235:genetics; D045726:Metalloproteases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D016868:Serratia Infections / Q000382:microbiology*; D012706:Serratia marcescens / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D037521:Virulence Factors
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D037521:Virulence Factors; D045726:Metalloproteases; D008666:Metalloendopeptidases; C095666:serralysin; D002118:Calcium
keywords: Airway cells; Cytotoxicity; Enterobacteriaceae; Metalloprotease; Virulence factor