Seawater-regulated genes for two-component systems and outer membrane proteins in myxococcus.
When salt-tolerant Myxococcus cells are moved to a seawater environment, they change their growth, morphology, and developmental behavior. Outer membrane proteins and signal transduction pathways may play important roles in this shift. Chip hybridization targeting the genes predicted to encode 226 two-component signal transduction pathways and 74 outer membrane proteins of M. xanthus DK1622 revealed that the expression of 55 corresponding genes in the salt-tolerant strain M. fulvus HW-1 was significantly modified (most were downregulated) by the presence of seawater. Sequencing revealed that these seawater-regulated genes are highly homologous in both strains, suggesting that they have similar roles in the lifestyle of Myxococcus. Seven of the genes that had been reported in M. xanthus DK1622 are involved in different cellular processes, such as fruiting body development, sporulation, or motility. The outer membrane (Om) gene Om031 had the most significant change in expression (downregulated) in response to seawater, while the two-component system (Tc) gene Tc105 had the greatest increase in expression. Their homologues MXAN3106 and MXAN4042 were knocked out in DK1622 to analyze their functions in response to changes in salinity. In addition to having increased salt tolerance, sporulation of the MXAN3106 mutant was enhanced compared to that of DK1622, whereas mutating gene MXAN4042 produced contrary results. The results indicated that the genes that are involved in the cellular processes that are significantly changed in response to salinity may also be involved the salt tolerance of Myxococcus cells. Regulating the expression levels of these multifunctional genes may allow cells to quickly and efficiently respond to changing conditions in coastal environments.
Pan
Hong-wei
HW
Shandong University, Jinan, People's Republic of China.
Liu
Hong
H
Liu
Ting
T
Li
Cheng-yun
CY
Li
Zhi-feng
ZF
Cai
Ke
K
Zhang
Cui-ying
CY
Zhang
Yong
Y
Hu
Wei
W
Wu
Zhi-hong
ZH
Li
Yue-zhong
YZ
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016940:Myxococcus / Q000235:genetics / Q000378:metabolism*; D054712:Salinity; D012623:Seawater / Q000032:analysis / Q000382:microbiology*; D015398:Signal Transduction; D012965:Sodium Chloride / Q000378:metabolism*
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D012965:Sodium Chloride