Nonproteolytic cleavage of aspartyl proline bonds in the cellulosomal scaffoldin subunit from Clostridium thermocellum.
Previous work from our group [Morage (Morgenstern), E., Bayer, E. A., and Lamed, R. (1991), Appl. Biochem. Biotechnol. 30, 129-136] has demonstrated an anomalous electrophoretic mobility pattern for scaffoldin, the 210-kDa cellulosome-integrating subunit of Clostridium thermocellum. Subsequent evidence [Morag, E., Bayer, E. A., and Lamed, R. (1992), Appl. Biochem. Biotechnol. 33, 205-217] indicated that the effect could be attributed to a nonproteolytic fragmentation of the subunit into a defined series of lower-molecular-weight bands. In the present work, a recombinant segment of the scaffoldin subunit was employed to determine the site(s) of bond breakage. An Asp-Pro sequence within the cohesin domain was identified to be the sensitive peptide bond. This sequence appears quite frequently in the large cellulosomal proteins, and the labile bond may be related to an as yet undescribed physiological role in the hydrolysis of cellulose by cellulosomes.
Department of Molecular, Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel.
R
R
Lamed
R
R
Kenig
E
E
Morag
S
S
Yaron
Y
Y
Shoham
E A
EA
Bayer
D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D003013:Clostridium / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D000097722:Cohesins
D001224:Aspartic Acid; D001426:Bacterial Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D005656:Fungal Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; D011392:Proline; D021122:Protein Subunits; D000097722:Cohesins; C074074:cellulose binding protein A, Clostridium cellulovorans