Genomic analysis of parallel-evolved cyanobacterium Synechocystis sp. PCC 6803 under acid stress.
Experimental evolution is a powerful tool for clarifying phenotypic and genotypic changes responsible for adaptive evolution. In this study, we isolated acid-adapted Synechocystis sp. PCC 6803 (Synechocystis 6803) strains to identify genes involved in acid tolerance. Synechocystis 6803 is rarely found in habitants with pH < 5.75. The parent (P) strain was cultured in BG-11 at pH 6.0. We gradually lowered the pH of the medium from pH 6.0 to pH 5.5 over 3 months. Our adapted cells could grow in acid stress conditions at pH 5.5, whereas the parent cells could not. We performed whole-genome sequencing and compared the acid-adapted and P strains, thereby identifying 11 SNPs in the acid-adapted strains, including in Fo F1-ATPase. To determine whether the SNP genes responded to acid stress, we examined gene expression in the adapted strains using quantitative reverse-transcription polymerase chain reaction. sll0914, sll1496, sll0528, and sll1144 expressions increased under acid stress in the P strain, whereas sll0162, sll0163, slr0623, and slr0529 expressions decreased. There were no differences in the SNP genes expression levels between the P strain and two adapted strains, except for sll0528. These results suggest that SNPs in certain genes are involved in acid stress tolerance in Synechocystis 6803.
Research Center for RNA Science, Research Institute for Science and Technology, Tokyo University of Science, 2641, Yamasaki, Noda, Chiba, 278-8510, Japan, junjiutiyama@yahoo.co.jp.
Junji
J
Uchiyama
Yu
Y
Kanesaki
Naoya
N
Iwata
Ryousuke
R
Asakura
Kento
K
Funamizu
Rizumu
R
Tasaki
Mina
M
Agatsuma
Hiroko
H
Tahara
Ayumi
A
Matsuhashi
Hirofumi
H
Yoshikawa
Satoru
S
Ogawa
Hisataka
H
Ohta
D001426:Bacterial Proteins / Q000235:genetics*; D023281:Genomics; D006863:Hydrogen-Ion Concentration; D013312:Stress, Physiological; D046939:Synechocystis / Q000235:genetics* / Q000502:physiology
D001426:Bacterial Proteins