Serpins in Prokaryotes

Irving, James A.; Steenbakkers, Peter J. M.; Lesk, Arthur M.; Camp, Huub J. M. Op den; Pike, Robert N.; Whisstock, James C.

doi:10.1093/oxfordjournals.molbev.a004012

Cited by 123 publications

(145 citation statements)

References 47 publications

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“…At the core of this mechanism is a hydrogen-bonding network which (in ATIII) chiefly involves His369 on s5A and Asn217 on s3A, together with Ser79 and Ser82. A sequence alignment of 219 serpin sequences (Irving et al, 2000) revealed that these four positions are highly conserved, with the above-mentioned side chains present in 78, 85, 93 and 72% of cases, respectively. The functional significance of the shutter region is underscored by the discovery of naturally occurring mutations of these residues that lead to dysfunction and disease.…”

Section: Shutter Regionmentioning

confidence: 99%

“…In contrast to canonical protease inhibitors, serpins employ a unique conformational mechanism for inactivation of their target protease (Farady & Craik, 2010). A comprehensive phylogenetic analysis of several hundred serpin sequences resulted in a classification into 16 clades; remarkably, the invertebrate members are typically arranged according to speciation (with schistosome serpins forming clade m), while the vertebrate proteins group into diverse clusters (Irving et al, 2000). Although most serpins are inhibitors of serine or cysteine proteases, several members have adopted different functions, acting, for example, as hormone transporters or molecular chaperones.…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional structure of a schistosome serpin revealing an unusual configuration of the helical subdomain

Granzin¹,

Huang²,

Topbaş³

et al. 2012

Acta Crystallogr D Biol Cryst

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Parasitic organisms are constantly challenged by the defence mechanisms of their respective hosts, which often depend on serine protease activities. Consequently, protease inhibitors such as those belonging to the serpin superfamily have emerged as protective elements that support the survival of the parasites. This report describes the crystal structure of ShSPI, a serpin from the trematode Schistosoma haematobium. The protein is exposed on the surface of invading cercaria as well as of adult worms, suggesting its involvement in the parasite–host interaction. While generally conforming to the well established serpin fold, the structure reveals several distinctive features, mostly concerning the helical subdomain of the protein. It is proposed that these peculiarities are related to the unique biological properties of a small serpin subfamily which is conserved among pathogenic schistosomes.

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Section: Shutter Regionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Three-dimensional structure of a schistosome serpin revealing an unusual configuration of the helical subdomain

Granzin¹,

Huang²,

Topbaş³

et al. 2012

Acta Crystallogr D Biol Cryst

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“…1,2 Serpins function as intracellular or extracellular regulators of a wide range of physiological processes such as complement activation, blood coagulation and apoptosis. Within the vertebrate immune system, they control proteases of the classical and innate complement systems, and are also potent inhibitors of many leukocyte granule proteases.…”

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confidence: 99%

Control of granzymes by serpins

2009

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Although proteolysis mediated by granzymes has an important role in the immune response to infection or tumours, unrestrained granzyme activity may damage normal cells. In this review, we discuss the role of serpins within the immune system, as specific regulators of granzymes. The well-characterised human granzyme B-SERPINB9 interaction highlights the cytoprotective function that serpins have in safeguarding lymphocytes from granzymes that may leak from granules. We also discuss some of the pitfalls inherent in using rodent models of granzyme-serpin interactions and the ways in which our understanding of serpins can help resolve some of the current, contentious issues in granzyme biology. Cell Death and Differentiation (2010) 17, 586-595; doi:10.1038/cdd.2009; published online 6 November 2009As described elsewhere in this series, granzymes are key mediators of cytotoxic lymphocyte (CL) function, exhibiting both intracellular and extracellular functions. Thus, it is imperative that their activities be tightly controlled. Too little activity reduces the effectiveness of the immune system, resulting in infection and cancer. Conversely, overactivity can lead to disease caused by tissue destruction and cellular apoptosis. This review focusses on the manner in which granzyme activity is controlled at the posttranslational level by members of the serpin superfamily.The serpin superfamily is an ever-expanding group of structurally related proteins, currently comprising approximately 1000 members across all kingdoms of life. 1,2 Serpins function as intracellular or extracellular regulators of a wide range of physiological processes such as complement activation, blood coagulation and apoptosis. Within the vertebrate immune system, they control proteases of the classical and innate complement systems, and are also potent inhibitors of many leukocyte granule proteases. Serpin StructureStructures of almost 100 serpins from viruses to humans have been determined and all conform to the same basic architecture first described in 1984. The fold comprises nine a-helices, three b-sheets and a variable reactive centre loop (RCL), which is the primary site of interaction with target proteases (Figure 1a). The first structure determined was human SERPINA1 cleaved within the RCL. 3 Surprisingly, it was found that the residues around the cleavage point were separated by almost 70 Å , with the N-terminal portion of the RCL inserted into b-sheet A to form a fully antiparallel sixstranded sheet. It has subsequently been shown that, in the native state, the RCL is solvent exposed, and that its insertion into b-sheet A is a consequence of the inhibitory mechanism. The RCL is flanked by two highly conserved motifs (the proximal and distal hinges) that permit its insertion into b-sheet A. Insertion is also facilitated by the breach and shutter regions that assist the opening of b-sheet A and by the movement of helix F. 4 The RCL is a critical determinant of serpin inhibitory specificity, acting as a pseudosubstrate and cleavage site for the...

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“…Serpins have been identified in animals, plants, insects, and certain viruses (1,2). More recently, serpins have been detected in prokaryotes (3). A search of genome data bases provides evidence for Ͼ500 serpins that are grouped into 17 clades (plus Ͼ10 unclassified orphans) based upon phylogenetic relationships (4).…”

mentioning

confidence: 99%

SRP-2 Is a Cross-class Inhibitor That Participates in Postembryonic Development of the Nematode Caenorhabditis elegans

Pak

Kumar

Tsu

et al. 2004

Journal of Biological Chemistry

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High molecular weight serpins are members of a large superfamily of structurally conserved proteins that inactivate target proteinases by a suicide substrate-like mechanism. In vertebrates, different clades of serpins distribute predominantly to either the intracellular or extracellular space. Although much is known about the function, structure, and inhibitory mechanism of circulating serpins such as ␣ 1 -antitrypsin (SERPINA1) and antithrombin III (SERPINC1), relatively little is known about the function of the vertebrate intracellular (clade B) serpins. To gain a better understanding of the biology of the intracellular serpins, we initiated a comparative genomics study using Caenorhabditis elegans as a model system. A screen of the C. elegans genomic and cDNA databases revealed nine serpin genes, tandemly arrayed on chromosome V. Although the C. elegans serpins represent a unique clade (L), they share significant functional homology with members of the clade B group of intracellular serpins, since they lack typical N-terminal signal peptides and reside intracellularly. To determine whether nematode serpins function as proteinase inhibitors, one family member, srp-2, was chosen for further characterization. Biochemical analysis of recombinant SRP-2 protein revealed SRP-2 to be a dual cross-class inhibitor of the apoptosis-related serine proteinase, granzyme B, and the lysosomal cysteine proteinases, cathepsins K, L, S, and V. Analysis of temporal and spatial expression indicated that SRP-2 was present during early embryonic development and highly expressed in the intestine and hypoderm of larval and adult worms. Transgenic animals engineered to overexpress SRP-2 were slow growing and/or arrested at the first, second, or third larval stages. These data suggest that perturbations of serpin-proteinase balance are critical for correct postembryonic development in C. elegans.Serpins are a unique class of proteinase inhibitors that irreversibly neutralize target proteinases by a mechanism involving the conformational distortion of the proteinase. Serpins have been identified in animals, plants, insects, and certain viruses (1, 2). More recently, serpins have been detected in prokaryotes (3). A search of genome data bases provides evidence for Ͼ500 serpins that are grouped into 17 clades (plus Ͼ10 unclassified orphans) based upon phylogenetic relationships (4). In humans, ϳ35 serpins have been identified. These serpins are distributed among nine clades (A-I), and most are secreted and function in the circulation or extracellular spaces. These serpins regulate proteinases involved in blood coagulation, fibrinolysis, complement activation, inflammation, and extracellular matrix remodeling. In contrast, serpins belonging to clade B reside predominantly intracellularly and have been implicated in regulating apoptosis, tumor progression, and metastasis (5). However, their biological functions in terms of an intact organism have not been well defined. To date, no naturally occurring mutations with an identifiable phenotype...

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Serpins in Prokaryotes

Cited by 123 publications

References 47 publications

Three-dimensional structure of a schistosome serpin revealing an unusual configuration of the helical subdomain

Three-dimensional structure of a schistosome serpin revealing an unusual configuration of the helical subdomain

Control of granzymes by serpins

SRP-2 Is a Cross-class Inhibitor That Participates in Postembryonic Development of the Nematode Caenorhabditis elegans

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