Table 2.
Characteristics of the Serum-Sensitive Mutants Identified in this Study
| NMB | NMA | Number of mutants | Gene | Predicted function in databases | S.I. |
| Capsule biosynthesis genes | |||||
| 0069 | 1 | siaB | sialic acid biosynthesis protein | 9.20 10−2 | |
| 0070 | 3 | siaA | sialic acid biosynthesis protein | <2.72 10−7 | |
| 0071 | 0198 | 1 | ctrA | capsule export outer-membrane protein | 9.36 10−3 |
| 0072 | 0197 | 1 | ctrB | capsule export inner-membrane protein | 3.47 10−4 |
| 0073 | 0196 | 1 | ctrC | capsule export inner-membrane protein | <2.72 10−7 |
| 0074 | 0195 | 2 | ctrD | capsule export ATP-binding protein | 8.34 10−3 |
| 0082 | 0186 | 2 | lipA | capsule phospholipid modification protein | <2.72 10−7 |
| 0083 | 0185 | 5 | lipB | capsule phospholipid modification protein | <2.72 10−7 |
| — | 1 | — | siaA-ctrAintergenic region | 3.66 10−4 | |
| LOS biosynthesis genes | |||||
| 0790 | 1001 | 3 | pgm | phosphoglucomutase | 1.06 10−3 |
| 0825 | 1034 | 1 | rfaE | ADP-heptose synthetase | 2.57 10−2 |
| 0828 | 1037 | 2 | rfaD | ADP-L-glycero-d-manno-heptose epimerase | 1.39 10−1 |
| 1704 | 1958 | 3 | lgtF | β-1,4-glucosyl transferase | 8.43 10−3 |
| 1926 | 0527 | 1 | IgtE | latco-N-neotetraose biosynthesis glycosyl transferase | 9.00 10−3 |
| 1929 | 0524 | 4 | lgtA | lacto-N-neotetraose biosynthesis glycosyl transferase | 3.07 10−2 |
| — | 1 | — | region downstream lgtE | 1.93 10−1 | |
| New genes | |||||
| 0065 | 2 | hypothetical protein | <2.72 10−7 | ||
| 0352 | 2135 | 1 | possible sugar isomerase | 4.44 10−3 | |
| 0638 | 0848 | 1 | galU | probable UTP-glucose-1-phosphate uridylyltransferase | 1.65 10−2 |
| 2076 | 0356 | 1 | possible transferase (aut family) | 8.99 10−3 |
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NMA and NMB denote the ORFs, in Z2491 and MC58 genomes, respectively, homologous to the sequence flanking the transposon insertion sites. Number of mutants indicates the number of insertions within a defined gene.
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S.I., Survival index defined as the ratio of the number of CFU of mutant to wild type after 5 h in native serum (n = 3).
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↵The transposon was inserted in the promoter region of the gene.
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↵This mutant presented a truncated LOS, but the affected gene could not be identified using the available sequences.
