Identification and functional analysis of glutamine transporter in .

BACKGROUND

, a biofilm-forming bacterium, possesses several transporters that function as import/export molecules. Among them, the PII protein family is composed of members that regulate glutamine synthesis in bacterial species.

OBJECTIVE

In this study, we characterized the function of the glutamine transporter in MT8148.

METHODS

The SMU.732 gene, corresponding to in , is homologous to the glutamine transporter gene in . We constructed a -inactivated mutant strain (GEMR) and a complement strain (comp-GEMR) and evaluated their biological functions.

RESULTS

Growth of GEMR was similar in the presence and absence of glutamine, whereas the growth rates of MT8148 and comp-GEMR were significantly lower in the presence of glutamine as compared to its absence. Furthermore, biofilms formed by MT8148 and comp-GEMR were significantly thicker than that formed by GEMR, while the GEMR strain showed a significantly lower survival rate in an acidic environment than the other strains. Addition of n-phenyl-2-naphthylamine, used to label of the membrane, led to increased fluorescence intensity of MT8148 and GEMR, albeit that was significantly lower in the latter.

CONCLUSIONS

These results suggest that is associated with glutamine transport in , especially the import of glutamine involved in biofilm formation.