The quorum sensing-dependent gene katG of Burkholderia glumae is important for protection from visible light.
Quorum sensing (QS) plays important roles in the pathogenicity of Burkholderia glumae, the causative agent of bacterial rice grain rot. We determined how QS is involved in catalase expression in B. glumae. The QS-defective mutant of B. glumae exhibited less catalase activity than wild-type B. glumae. A beta-glucuronidase assay of a katG::Tn3-gusA78 reporter fusion protein revealed that katG expression is under the control of QS. Furthermore, katG expression was upregulated by QsmR, a transcriptional activator for flagellar-gene expression that is regulated by QS. A gel mobility shift assay confirmed that QsmR directly activates katG expression. The katG mutant produced toxoflavin but exhibited less severe disease than BGR1 on rice panicles. Under visible light conditions and a photon flux density of 61.6 micromol(-1) m(-2), the survival rate of the katG mutant was 10(5)-fold lower than that of BGR1. This suggests that KatG is a major catalase that protects bacterial cells from visible light, which probably results in less severe disease caused by the katG mutant.
Chun
Heejin
H
Department of Agricultural Biotechnology, Seoul National University, Seoul , Republic of Korea.
Choi
Okhee
O
Goo
Eunhye
E
Kim
Nayeon
N
Kim
Hongsup
H
Kang
Yongsung
Y
Kim
Jinwoo
J
Moon
Jae Sun
JS
Hwang
Ingyu
I
D001426:Bacterial Proteins / Q000235:genetics*; D019117:Burkholderia / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial; D008027:Light; D050296:Microbial Viability / Q000235:genetics* / Q000528:radiation effects*; D009154:Mutation; D012275:Oryza / Q000382:microbiology; D011744:Pyrimidinones / Q000378:metabolism; D053038:Quorum Sensing / Q000235:genetics*; D014227:Triazines / Q000378:metabolism
D001426:Bacterial Proteins; D011744:Pyrimidinones; D014227:Triazines; C009570:toxoflavin