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Biochem J. 2001 Apr 1;355(Pt 1):155-65.

Pectate lyase 10A from Pseudomonas cellulosa is a modular enzyme containing a family 2a carbohydrate-binding module.

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  • 1School of Sciences, University of Sunderland, Sunderland SR1 3SD, U.K.

Abstract

Pectate lyase 10A (Pel10A) enzyme from Pseudomonas cellulosa is composed of 649 residues and has a molecular mass of 68.5 kDa. Sequence analysis revealed that Pel10A contained a signal peptide and two serine-rich linker sequences that separate three modules. Sequence similarity was seen between the 9.2 kDa N-terminal module of Pel10A and family 2a carbohydrate-binding modules (CBMs). This N-terminal module of Pel10A was shown to encode an independently functional module with affinity to crystalline cellulose. A high sequence identity of 66% was seen between the 14.2 kDa central module of Pel10A and the functionally uncharacterized central modules of the xylan-degrading enzymes endoxylanase 10B, arabinofuranosidase 62C and esterase 1D, also from P. cellulosa. The 35.8 kDa C-terminal module of Pel10A was shown to have 30 and 36% identities with the family 10 pectate lyases from Azospirillum irakense and an alkaliphilic strain of Bacillus sp. strain KSM-P15, respectively. This His-tagged C-terminal module of the Pel10A was shown to encode an independent catalytic module (Pel10Acm). Pel10Acm was shown to cleave pectate and pectin in an endo-fashion and to have optimal activity at pH 10 and in the presence of 2 mM Ca2+. Highest enzyme activity was detected at 62 degrees C. Pel10Acm was shown to be most active against pectate (i.e. polygalacturonic acid) with progressively less activity against 31, 67 and 89% esterified citrus pectins. These data suggest that Pel10A has a preference for sequences of non-esterified galacturonic acid residues. Significantly, Pel10A and the P. cellulosa rhamnogalacturonan lyase 11A, in the accompanying article [McKie, Vincken, Voragen, van den Broek, Stimson and Gilbert (2001) Biochem. J. 355, 167-177], are the first CBM-containing pectinases described to date.

PMID:
11256960
[PubMed - indexed for MEDLINE]
PMCID:
PMC1221723
Free PMC Article
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