Two genes encoding an endoglucanase and a cellulose-binding protein are clustered and co-regulated by a TTA codon in Streptomyces halstedii JM8.
Streptomyces halstedii JM8 Cel2 is an endoglucanase of 28 kDa that is first produced as a protein of 42 kDa (p42) and is later processed at its C-terminus. Cel2 displays optimal activity towards CM-cellulose at pH6 and 50 degrees C and shows no activity against crystalline cellulose or xylan. The N-terminus of p42 shares similarity with cellulases included in family 12 of the beta-glycanases and the C-terminus shares similarity with bacterial cellulose-binding domains included in family II. This latter domain enables the precursor to bind so tightly to Avicel that it can only be eluted by boiling in 10% (w/v) SDS. Another open reading frame (ORF) situated 216 bp downstream from the p42 ORF encodes a protein of 40 kDa (p40) that does not have any clear hydrolytic activity against cellulosic or xylanosic compounds, but shows high affinity for Avicel (crystalline cellulose). The p40 protein is processed in old cultures to give a protein of 35 kDa that does not bind to Avicel. Translation of both ORFs is impaired in Streptomyces coelicolor bldA mutants, suggesting that a TTA codon situated at the fourth position of the first ORF is responsible for this regulation. S1 nuclease protection experiments demonstrate that both ORFs are co-transcribed.
Garda
A L
AL
Instituto de Microbiología Bioquímica, Consejo Superior de Investigaciones Científicas, (CSIC)/Universidad de Salamanca, Campus Miguel de Unamuno, Avda, Campo Charro s/n, Salamanca, Spain.
Fernández-Abalos
J M
JM
Sánchez
P
P
Ruiz-Arribas
A
A
Santamaría
R I
RI
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D002480:Cellulase; D002482:Cellulose / Q000378:metabolism*; D003062:Codon / Q000235:genetics*; D004274:DNA, Recombinant / Q000235:genetics; D004790:Enzyme Induction; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D006026:Glycoside Hydrolases / Q000096:biosynthesis / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D014176:Protein Biosynthesis; D012329:RNA, Bacterial; D012356:RNA, Transfer, Leu / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics*
D001426:Bacterial Proteins; C107344:BldA tRNA, Streptomyces coelicolor; D002352:Carrier Proteins; D003062:Codon; D004274:DNA, Recombinant; D012329:RNA, Bacterial; D012356:RNA, Transfer, Leu; D011993:Recombinant Fusion Proteins; C106457:cellulose-binding protein p40, Streptomyces halstedi; D002482:Cellulose; D006026:Glycoside Hydrolases; C106456:CELA2 protein, Streptomyces halstedii; D002480:Cellulase