Strategy for enhancing adenosine production under the guidance of transcriptional and metabolite pool analysis.
OBJECTIVE
To rationally identify targets for enhancing adenosine production, transcription level of genes involved in adenosine synthesis of Bacillus subtilis XGL was detected during the fermentation process, complemented with metabolite pool analysis.


RESULTS
PurR-regulated genes (pur operon and purA) and prs were down-regulated and 5-phosphoribosyl 1-pyrophosphate (PRPP) decreased considerably after 24 h when adenosine significantly accumulated. Since PRPP could strongly antagonize the binding of PurR to its targets, it was inferred that down-regulation of pur operon and purA might be due to a low PRPP pool, which was confirmed by metabolite analysis. So desensitized prs responsible for PRPP synthesis was overexpressed, resulting in increased PRPP concentration and pur operon transcription. To further enhance the adenosine production, desensitized purF and prs were co-overexpressed with integrating additional copy of purA to B. subtilis XGL genome, resulting in 24.3 % (1.29 g/g DCW) higher adenosine production than that by B. subtilis XG.


CONCLUSIONS
Overexpression of prs, purF and purA under the guidance of transcriptional and metabolite pool analysis significantly increased adenosine production. Strategies used in this study have potential applications for rational modification of industrial microorganisms.
College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China, zcl@tust.edu.cn.
Chenglin
C
Zhang
Shanshan
S
Du
Yue
Y
Liu
Xixian
X
Xie
Qingyang
Q
Xu
Ning
N
Chen
D000241:Adenosine / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D060847:Metabolic Engineering; D053858:Metabolic Networks and Pathways / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; C065825:PurR protein, Bacteria; D012097:Repressor Proteins; D000241:Adenosine