Analysis of cohesin-dockerin interactions using mutant dockerin proteins.
Clostridial cellulosomes are cellulolytic complexes that are formed by highly specific interactions between one of the repeated cohesin modules present in the scaffolding protein and a dockerin module of the catalytic components. Although Clostridium thermocellum Xyn11A dockerin has a typical C. thermocellum dockerin sequence, in which two amino acid residues are species specifically conserved within the two segments of the dockerin modules, it can recognize Clostridium josui cohesin modules in a non-species-specific manner. The importance of these two conserved amino acids, which are part of the recognition site of the cohesin and dockerin interaction, was investigated by introducing mutations into the first and/or the second segments of the Xyn11A dockerin. Mutations in the first segment did not affect the interactions between dockerin and C. thermocellum and C. josui cohesins. However, mutations in the second segment prevented binding to cohesin proteins. A second round of mutations within the first segment re-established the affinity for both the C. thermocellum and the C. josui cohesins. However, this was not observed for a 'conventional' dockerin, Xyn10C. These results suggest that the combination of the first and second dockerin segments is important for the target recognition.
Applied Microbiology Laboratory, Graduate School of Bioresources, Mie University, Tsu, Japan.
Kazutaka
K
Sakka
Yuka
Y
Sugihara
Sadanari
S
Jindou
Makiko
M
Sakka
Minoru
M
Inagaki
Kazuo
K
Sakka
Tetsuya
T
Kimura
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002480:Cellulase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003013:Clostridium / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D048013:Acetivibrio thermocellus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D016415:Sequence Alignment; D000097722:Cohesins
D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D002480:Cellulase; D002868:Chromosomal Proteins, Non-Histone; D009097:Multienzyme Complexes; D000097722:Cohesins; C473132:cellulosome, Clostridium