Bacterial invasion of eukaryotic cells can be mediated by actin-hydrolysing metalloproteases grimelysin and protealysin

Bozhokina, Ekaterina; Tsaplina, Olga; Ефремова, Т. В.; Kever, L. V.; Demidyuk, Ilya V.; Kostrov, Sergey V.; Adam, Thomas C.; Komissarchik, Ya. Yu.; Khaitlina, Sofia

doi:10.1042/cbi20100314

Cited by 45 publications

(52 citation statements)

References 37 publications

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“…A variety of model systems have demonstrated that secreted proteases are key virulence factors, facilitating invasion of bacteria into mammalian cells, cleavage of host innate immune factors such as immunoglobulins and surfactant protein D, and disruption of tight junctions and epithelial cell integrity (12,21,26,51). In polymicrobial infections, proteases could potentiate virulence by other microbes, not only through enabling bacterial invasion but also through degrading host immune components and activating host proteins, such as matrix metalloproteases (52).…”

Section: Discussionmentioning

confidence: 99%

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Identification of SlpB, a Cytotoxic Protease from Serratia marcescens

et al. 2015

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The Gram-negative bacterium and opportunistic pathogen Serratia marcescens causes ocular infections in healthy individuals. Secreted protease activity was characterized from 44 ocular clinical isolates, and a higher frequency of protease-positive strains was observed among keratitis isolates than among conjunctivitis isolates. A positive correlation between protease activity and cytotoxicity to human corneal epithelial cells in vitro was determined. Deletion of prtS in clinical keratitis isolate K904 reduced, but did not eliminate, cytotoxicity and secreted protease production. This indicated that PrtS is necessary for full cytotoxicity to ocular cells and implied the existence of another secreted protease(s) and cytotoxic factors. Bioinformatic analysis of the S. marcescens Db11 genome revealed three additional open reading frames predicted to code for serralysin-like proteases noted here as slpB, slpC, and slpD. Induced expression of prtS and slpB, but not slpC and slpD, in strain PIC3611 rendered the strain cytotoxic to a lung carcinoma cell line; however, only prtS induction was sufficient for cytotoxicity to a corneal cell line. Strain K904 with deletion of both prtS and slpB genes was defective in secreted protease activity and cytotoxicity to human cell lines. PAGE analysis suggests that SlpB is produced at lower levels than PrtS. Purified SlpB demonstrated calcium-dependent and AprI-inhibited protease activity and cytotoxicity to airway and ocular cell lines in vitro. Lastly, genetic analysis indicated that the type I secretion system gene, lipD, is required for SlpB secretion. These genetic data introduce SlpB as a new cytotoxic protease from S. marcescens. Microbial keratitis (MK) is a blinding disease with poor visual outcomes even with effective antibiotics and antifungal agents (1-3). In addition to being a major cause of hospital-acquired infections, such as ventilator-associated pneumonia (4, 5), Serratia marcescens is a common cause of MK (1, 2, 6-8), yet the virulence factors involved in this process are poorly understood. In general, bacterial secreted factors, including hemolysins and proteases, contribute to the pathogenesis of bacterial corneal infections (9-12). There are several studies characterizing the importance of proteases from S. marcescens isolates in ocular infections, most recently reviewed by Matsumoto (13). Serralysin is a cytotoxic factor capable of killing mammalian cells in vitro (14,15). Purified serralysin is sufficient to cause keratitis when injected into rabbit eyes and promotes the spread of bacteria through the corneal stroma (16-18). Additionally, serralysin can degrade components of the human immune system, such as PAR-2, in vitro, and this may impact corneal pathogenesis (13,(19)(20)(21). Serralysin, and serralysin family metalloproteases, such as alkaline protease from Pseudomonas aeruginosa, can proteolyze mammalian cell surface proteins, thereby modulating cell physiology. A recent example is the protease-mediated activation of the epithelial sodium channel, lea...

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Section: Discussionmentioning

confidence: 99%

“…A recent example is the protease-mediated activation of the epithelial sodium channel, leading to a cell surface that is more amenable to bacterial colonization (22,23). Several bacteria, including Serratia species, invade eukaryotic airway cells in a protease-dependent manner (24)(25)(26)(27).…”

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Identification of SlpB, a Cytotoxic Protease from Serratia marcescens

et al. 2015

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“…A recently described metalloprotease from S. grimesii, grimelysin, is proteolytic for actin (46). E. coli that expressed grimelysin was able to invade Hep-2 cells, so this metalloprotease may allow bacterial internalization into eukaryotic cells (47).…”

Section: Enzymes Produced By Serratia Speciesmentioning

confidence: 99%

Serratia Infections: from Military Experiments to Current Practice

2011

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SUMMARY Serratia species, in particular Serratia marcescens , are significant human pathogens. S. marcescens has a long and interesting taxonomic, medical experimentation, military experimentation, and human clinical infection history. The organisms in this genus, particularly S. marcescens , were long thought to be nonpathogenic. Because S. marcescens was thought to be a nonpathogen and is usually red pigmented, the U.S. military conducted experiments that attempted to ascertain the spread of this organism released over large areas. In the process, members of both the public and the military were exposed to S. marcescens , and this was uncovered by the press in the 1970s, leading to U.S. congressional hearings. S. marcescens was found to be a certain human pathogen by the mid-1960s. S. marcescens and S. liquefaciens have been isolated as causative agents of numerous outbreaks and opportunistic infections, and the association of these organisms with point sources such as medical devices and various solutions given to hospitalized patients is striking. Serratia species appear to be common environmental organisms, and this helps to explain the large number of nosocomial infections due to these bacteria. Since many nosocomial infections are caused by multiply antibiotic-resistant strains of S. marcescens , this increases the danger to hospitalized patients, and hospital personnel should be vigilant in preventing nosocomial outbreaks due to this organism. S. marcescens , and probably other species in the genus, carries several antibiotic resistance determinants and is also capable of acquiring resistance genes. S. marcescens and S. liquefaciens are usually identified well in the clinical laboratory, but the other species are rare enough that laboratory technologists may not recognize them. 16S rRNA gene sequencing may enable better identification of some of the less common Serratia species.

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“…This was the first finding that any S. proteamaculans strain was capable of eukaryotic cell invasion. Similarly, S. grimesii produces grimelysin, a novel metalloprotease, which has specific actin-hydrolyzing activity and mediates HEp-2 cell invasion (31).…”

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Molecular Characterization of Protease Activity in Serratia sp. Strain SCBI and Its Importance in Cytotoxicity and Virulence

Petersen

Tisa

2014

J Bacteriol

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A newly recognized Serratia species, termed South African Caenorhabditis briggsae isolate (SCBI), is both a mutualist of the nematode Caenorhabditis briggsae KT0001 and a pathogen of lepidopteran insects. Serratia sp. strain SCBI displays high proteolytic activity, and because secreted proteases are known virulence factors for many pathogens, the purpose of this study was to identify genes essential for extracellular protease activity in Serratia sp. strain SCBI and to determine what role proteases play in insect pathogenesis and cytotoxicity. A bank of 2,100 transposon mutants was generated, and six SCBI mutants with defective proteolytic activity were identified. These mutants were also defective in cytotoxicity. The mutants were found defective in genes encoding the following proteins: alkaline metalloprotease secretion protein AprE, a BglB family transcriptional antiterminator, an inosine/xanthosine triphosphatase, GidA, a methyl-accepting chemotaxis protein, and a PIN domain protein. Gene expression analysis on these six mutants showed significant downregulation in mRNA levels of several different types of predicted protease genes. In addition, transcriptome sequencing (RNA-seq) analysis provided insight into how inactivation of AprE, GidA, and a PIN domain protein influences motility and virulence, as well as protease activity. Using quantitative reverse transcription-PCR (qRT-PCR) to further characterize expression of predicted protease genes in wild-type Serratia sp. SCBI, the highest mRNA levels for the alkaline metalloprotease genes (termed prtA1 to prtA4) occurred following the death of an insect host, while two serine protease and two metalloprotease genes had their highest mRNA levels during active infection. Overall, these results indicate that proteolytic activity is essential for cytotoxicity in Serratia sp. SCBI and that its regulation appears to be highly complex.

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Bacterial invasion of eukaryotic cells can be mediated by actin-hydrolysing metalloproteases grimelysin and protealysin

Cited by 45 publications

References 37 publications

Identification of SlpB, a Cytotoxic Protease from Serratia marcescens

Identification of SlpB, a Cytotoxic Protease from Serratia marcescens

Serratia Infections: from Military Experiments to Current Practice

Molecular Characterization of Protease Activity in Serratia sp. Strain SCBI and Its Importance in Cytotoxicity and Virulence

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