title: The structure of the cysteine protease and lectin-like domains of Cwp84, a surface layer-associated protein from Clostridium difficile.
abstract: Clostridium difficile is a major problem as an aetiological agent for antibiotic-associated diarrhoea. The mechanism by which the bacterium colonizes the gut during infection is poorly understood, but undoubtedly involves a myriad of components present on the bacterial surface. The mechanism of C. difficile surface-layer (S-layer) biogenesis is also largely unknown but involves the post-translational cleavage of a single polypeptide (surface-layer protein A; SlpA) into low- and high-molecular-weight subunits by Cwp84, a surface-located cysteine protease. Here, the first crystal structure of the surface protein Cwp84 is described at 1.4 Å resolution and the key structural components are identified. The truncated Cwp84 active-site mutant (amino-acid residues 33-497; C116A) exhibits three regions: a cleavable propeptide and a cysteine protease domain which exhibits a cathepsin L-like fold followed by a newly identified putative carbohydrate-binding domain with a bound calcium ion, which is referred to here as a lectin-like domain. This study thus provides the first structural insights into Cwp84 and a strong base to elucidate its role in the C. difficile S-layer maturation mechanism.
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, England.
authors.forename: William J
authors.initials: WJ
authors.lastname: Bradshaw
authors.affiliation: Public Health England, Porton Down, Salisbury SP4 0JG, England.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Kirby
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, England.
authors.forename: Nethaji
authors.initials: N
authors.lastname: Thiyagarajan
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, England.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Chambers
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, England.
authors.forename: Abigail H
authors.initials: AH
authors.lastname: Davies
authors.affiliation: Public Health England, Porton Down, Salisbury SP4 0JG, England.
authors.forename: April K
authors.initials: AK
authors.lastname: Roberts
authors.affiliation: Public Health England, Porton Down, Salisbury SP4 0JG, England.
authors.forename: Clifford C
authors.initials: CC
authors.lastname: Shone
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, England.
authors.forename: K Ravi
authors.initials: KR
authors.lastname: Acharya
mesh_terms: D000595:Amino Acid Sequence; D016360:Clostridioides difficile / Q000737:chemistry*; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D057056:Cysteine Proteases / Q000737:chemistry*; D017931:DNA Primers; D037102:Lectins / Q000737:chemistry*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D037102:Lectins; D057056:Cysteine Proteases; C524258:Cwp84 protein, Clostridium difficile; D003546:Cysteine Endopeptidases
keywords: Clostridium difficile; Cwp84; surface layer-associated protein