Cloning and DNA Sequencing of the Genes EncodingClostridium josui Scaffolding Protein CipA and Cellulase CelD and Identification of Their Gene Products as Major Components of the Cellulosome
ABSTRACT The Clostridium josui cipA and celD genes, encoding a scaffolding-like protein (CipA) and a putative cellulase (CelD), respectively, have been cloned and sequenced. CipA, with an estimated molecular weight of 120,227, consists of an N-terminal signal peptide, a cellulose-binding domain of family III, and six successive cohesin domains. The molecular architecture of C. josuiCipA is similar to those of the scaffolding proteins reported so far, such as Clostridium thermocellum CipA, Clostridium cellulovorans CbpA, and Clostridium cellulolyticumCipC, but C. josui CipA is considerably smaller than the other scaffolding proteins. CelD consists of an N-terminal signal peptide, a family 48 catalytic domain of glycosyl hydrolase, and a dockerin domain. N-terminal amino acid sequence analysis of theC. josui cellulosomal proteins indicates that both CipA and CelD are major components of the cellulosome.