A serpin in the cellulosome of the anaerobic fungus Piromyces sp. strain E2.
A gene encoding a novel component of the cellulolytic complex (cellulosome) of the anaerobic fungus Piromyces sp. strain E2 was identified. The encoded 538 amino acid protein, named celpin, consists of a signal peptide, a positively charged domain of unknown function followed by two fungal dockerins, typical for components of the extracellular fungal cellulosome. The C-terminal end consists of a 380 amino acid serine proteinase inhibitor (or serpin) domain homologue, sharing 30% identity and 50% similarity to vertebrate and bacterial serpins. Detailed protein sequence analysis of the serpin domain revealed that it contained all features of a functional serpin. It possesses the conserved amino acids present in more than 70% of known serpins, and it contained the consensus of inhibiting serpins. Because of the confined space of the fungal cellulosome inside plant tissue and the auto-proteolysis of plant material in the rumen, the fungal serpin is presumably involved in protection of the cellulosome against plant proteinases. The celpin protein of Piromyces sp. strain E2 is the first non-structural, non-hydrolytic fungal cellulosome component. Furthermore, the celpin protein of Piromyces sp. strain E2 is the first representative of a serine proteinase inhibitor of the fungal kingdom.
Department of Microbiology, IWWR, Radboud University Nijmegen, Toernooiveld 1, NL-6525ED Nijmegen, The Netherlands.
Peter J M
PJ
Steenbakkers
James A
JA
Irving
Harry R
HR
Harhangi
Willem J C
WJ
Swinkels
Anna
A
Akhmanova
Rembrandt
R
Dijkerman
Mike S M
MS
Jetten
Chris
C
van der Drift
James C
JC
Whisstock
Huub J M
HJ
Op den Camp
D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001483:Base Sequence; D044603:Cellulosomes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D020089:Piromyces / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D015843:Serpins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D005656:Fungal Proteins; D015843:Serpins