PUL ID

PUL0166

PubMed

16788175, J Bacteriol. 2006 Jul;188(13):4663-72. doi: 10.1128/JB.00125-06.

Characterization method

enzyme activity assay,RT-PCR

Genomic accession number

NC_016776.1

Nucelotide position range

3710042-3720606

Substrate

starch

Loci

BF638R_RS15150-BF638R_RS15170

Species

Bacteroides fragilis/817

Degradation or Biosynthesis

degradation

Cluster number

1

Gene name

Gene position

Gene type

Found by CGCFinder?

- 1 - 813 (-) CAZyme: GH13_10|GH13 Yes
- 918 - 2516 (-) other Yes
- 2552 - 4171 (-) TC: gnl|TC-DB|Q8A1G2|8.A.46.1.1 Yes
- 4182 - 7190 (-) TC: gnl|TC-DB|Q45780|1.B.14.6.1 Yes
- 7506 - 8516 (+) TF: DBD-Pfam|LacI,DBD-SUPERFAMILY|0036955 No

PUL ID

PUL0166

PubMed

16788175, J Bacteriol. 2006 Jul;188(13):4663-72. doi: 10.1128/JB.00125-06.

Title

Characterization of the primary starch utilization operon in the obligate anaerobe Bacteroides fragilis: Regulation by carbon source and oxygen.

Author

Spence C, Wells WG, Smith CJ

Abstract

The opportunistic pathogen Bacteroides fragilis is a commensal organism in the large intestine, where it utilizes both dietary and host-derived polysaccharides as a source of carbon and energy. In this study, a four-gene operon required for starch utilization was identified. The operon also was found to be oxygen responsive and thus was designated osu for oxygen-induced starch utilization. The first three genes in the operon were predicted to encode outer membrane proteins involved in starch binding, and a fourth gene, osuD, encoded an amylase involved in starch hydrolysis. Insertional mutation of the osuA gene (Omega osuA) resulted in the inability to utilize starch or glycogen and an insertional mutation into the osuD gene (Omega osuD) was severely impaired for growth on starch media. Transcriptional studies indicated that maltose, maltooligosaccharides, and starch were inducers of osu expression and that maltose was the strongest inducer. A transcriptional activator of osuABCD, OsuR, was identified and found to mediate maltose induction. The Omega osuA and Omega osuD mutants were able to grow on maltose but not starch, whereas a mutation in osuR abolished growth on both substrates, indicating that additional genes under the control of OsuR are needed for maltose utilization. The osuABCD operon also was induced by exposure to oxygen and was shown to be part of the oxidative stress response important for aerotolerance of B. fragilis. Transcriptional analyses showed that osuA was induced 20-fold by oxygen, but OsuR was not required for this activation. Analysis of osu mutants suggested that expression of the operon was important for survival during oxygen exposure but not to hydrogen peroxide stress.