Hemicellulolytic and cellulolytic functions of the domains of a β-mannanase cloned from Caldicellosiruptor saccharolyticus

Tracy Frangos, Denise Bullen, Peter Bergquist, Roy Daniel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Various combinations of the four domains of the multifunctional mannanase from Caldicellosiruptor saccharolyticus have been cloned and expressed in Escherichia coli. The four domains comprise two catalytic domains (1 and 4), and two putative cellulose binding domains (2 and 3). Each of the six gene products (Man1, Man123, Man1234, Man23, Man234 and Man4) was partially purified by heat treatment.The enzymes Man1234, Man123 and Man1 exhibited activity on mannans, and Man1234, Man234 and Man4 exhibited activity on xylan and carboxymethylcellulose (CMC). For the complete enzyme (Man1234) all activities were of the same order of magnitude. Activities were additive against a mixture of mannan and xylan or mannan and CMC (but not xylan and CMC). The expression product Man23 exhibited activity on none of the substrates tested, nor did its presence influence thermostability or significantly reduce the K(m) value for any of the substrates. However, when expressed in combination with domains 1 or 4 it greatly increased their activity.We conclude that domain 1 catalyses mannan hydrolysis and domain 4 catalyses xylan and CMC hydrolysis at the same active site: domains 2 and 3 have no obvious function, since they do not reduce substrate K(m) nor affect thermostability. However, their effect on rates of substrate hydrolysis may indicate a role influencing the conformation of the adjacent catalytic domains. Copyright (C) 1999 Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)853-859
Number of pages7
JournalInternational Journal of Biochemistry and Cell Biology
Issue number8
Publication statusPublished - Aug 1999


  • Caldicellosiruptor saccharolyticus
  • Cellulase
  • Enzyme domains
  • Mannanase
  • Xylanase


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