TABLE 2.
Effects of Mg2+ and K+ on the growth of thermosensitive mutants from Zymomonas mobilis TISTR 548.
| Group | Tn10-inserted genea | Strain | Function | Protein type |
Growthb |
Effect of MgCl2c |
Effect of KClc |
||
| 38°C | 39°C | 39.5°C | Ratio (%) | Ratio (%) | |||||
| WT (TISTR 548) | ++++ | ++++ | +++ | 108±10 | 105 ± 15 | ||||
| General metabolism | ZZ6_0707 | TC01 | Glucose sorbosone dehydrogenase | Soluble | + | + | − | 114 ± 8 | 103 ± 23 |
| ZZ6_1376 | TC03 | 5,10-methylenetetrahydrofolate reductase | Soluble | ++++ | ++++ | + | 126 ± 1 | 118 ± 4 | |
| Membrane stabilization | ZZ6_1146 | TE12 | Glucosamine/fructose 6-phoshate aminotransferase | Membrane | + | + | − | 119 ± 6 | 328 ± 14 |
| ZZ6_0929 | 3-24 | Glycosyl transferase group 1 | Soluble | + | − | − | 138 ± 6 | 146 ± 2 | |
| ZZ6_0923 | TC04 | Phospholipase D/transphosphatidylase | Membrane | − | − | − | 176 ± 7 | 177 ± 10 | |
| ZZ6_1551 | C12-36 | Squalene hopene cyclase (Shc) | Soluble | − | − | − | 131 ± 4 | 98 ± 13 | |
| ZZ6_1046 | C11-44 | Tol/Pal system component TolQ | Membrane | + | + | − | 157 ± 5 | 519 ± 4 | |
| ZZ6_1043 | 1-2 | Tol/Pal system component TolB | Soluble | + | + | + | 115 ± 9 | 110 ± 5 | |
| ZZ6_1254 | C31-23 | Protein export membrane protein SecD | Membrane | − | − | − | 112 ± 5 | 223 ± 7 | |
| ZZ6_1477 | TC15 | Preprotein translocase subunit Tim44 | Membrane | − | − | − | 151 ± 11 | 127 ± 2 | |
| ZZ6_0158 | TC14 | Autotransporter secretion inner membrane protein TamB | Membrane | + | − | − | 118 ± 9 | 165 ± 10 | |
| ZZ6_1210 | C13-36 | Competence protein ComEC | Membrane | − | − | − | 126 ± 7 | 33 ± 4 | |
| ZZ6_0840 | TC11 | Hypothetical transmembrane protein | Membrane | − | − | − | 181 ± 8 | 126 ± 4 | |
| ZZ6_0541 | TC09 | Hypothetical transmembrane protein | Membrane | ++++ | +++ | + | 119 ± 1 | 116 ± 5 | |
| Transporter | ZZ6_1289 | 1-10 | Putative Fe2+/Mn2+ transporter | Membrane | − | − | − | 231 ± 3 | 151 ± 4 |
| DNA repair | ZZ6_0616 | F32 | DNA repair protein RadC | Soluble | ++++ | +++ | + | 113 ± 9 | 96 ± 4 |
| ZZ6_0934 | C12-43 | Exonuclease VII (XseA) | Soluble | − | − | − | 156 ± 6 | 146 ± 1 | |
| ZZ6_0681 | TC10 | DNA repair protein RadA | Soluble | + | + | − | 101 ± 5 | 62 ± 8 | |
| tRNA/rRNA modification | ZZ6_0023 | C12-44 | tRNA/rRNA methyltransferase (SpoU) | Soluble | +++ | ++ | ++ | 117 ± 11 | 116 ± 12 |
| Protein quality control | ZZ6_1659 | C21-17 | Zn-dependent peptidase | Soluble | ++++ | +++ | ++ | 99 ± 10 | 104 ± 16 |
| ZZ6_0980 | TC05 | Serine protease DegP | Soluble | − | − | − | 153 ± 5 | 172 ± 3 | |
| Translational regulation | ZZ6_0702 | TC12 | ATP-dependent helicase HrpB | Soluble | − | − | − | 98 ± 1 | 212 ± 4 |
| Cell division | ZZ6_0979 | TE19 | ParA/MinD-like ATPase | Soluble | − | − | − | 114 ± 8 | 90 ± 11 |
| Transcriptional regulation | ZZ6_0019 | C31-15 | Trp repressor-binding protein WrbA | Soluble | − | − | − | 137 ± 4 | 577 ± 8 |
| Others | ZZ6_0962 | C12-37 | Pseudogene | + | + | − | 161 ± 9 | 121 ± 7 | |
| ZZ6_0861 | TC13 | Hypothetical protein | Soluble | + | + | − | 53 ± 3 | 327 ± 2 | |
aThirty-six thermotolerant genes were identified, and they were classified into 10 groups (Charoensuk et al., 2017). bThe growth of these mutants at 38, 39, and 39.5°C compared with that of the parental strain on YPD medium. The symbols “+” represent the degree of cell growth of mutants at a critical high temperature compared with that of the parental strain, whereas “−” indicates no growth. cThe ratio (%) was calculated from the OD550 values for cells grown at 39.5°C for 24 h with 5 mM MgCl2 or 30 mM KCl divided by those cells grown without metals. Values represent means ± standard deviations of three replicates. Bold values indicate a ratio of >1.5 or <0.5 against the parental strain.