PII proteins in mycobacteria

DELFINA ENSINCK; GAGO GABRIELA; LUCIANO F. HUERGO; GRAMAJO HUGO; DIACOVICH LAUTARO

Congreso; X MEETING OF LATIN AMERICAN SOCIETY OF TUBERCULOSIS AND OTHER MYCOBACTERIOSIS (SLAM-TB); 2021

LATIN AMERICAN SOCIETY OF TUBERCULOSIS AND OTHER MYCOBACTERIOSIS (SLAM-TB)

The PII proteins are a family of signal transduction protein widely distributed within bacteria, archaea and the plastids of plants. Remarkably, PII proteins are able to sense signals from the carbon, nitrogen and energy status, changing their conformational state. These two conformation states define a differential interaction with diverse target proteins, mainly of which are involved in nitrogen assimilatory pathway. In some bacteria, PII proteins are also involved in carbon metabolism by modulating the activity of acyl-CoA carboxylases. The function of PII proteins in mycobacteria, including the pathogen Mycobacterium tuberculosis, has not be addressed.In order to elucidate the role of PII proteins in mycobacteria, we constructed an in-frame deletion mutant of PII gene in Mycobacterium smegmatis by homologous recombination. This mutant showed no growth defect in media containing ammonia or nitrate as sole nitrogen source. On the other hand, when this strain was growth in nitrite the mutant presented a prolonged lag phase compared to de wild type strain and reached lower optical densities. This effect was exacerbated when the nitrite concentration was increased. Regarding the modulation of acyl-CoA- activity, we analyzed the acetyl-CoA and propionil-CoA activity in protein extracts of M. smegmatis grown in an ammonia limiting condition, and after an ammonia shock. However, no change in acyl-CoA activity was observed.In conclusion, we showed that PII is a non-essential protein for M. smegmatis and nor participate in ACCase activity modulation. However, it seems to be involved in nitrite assimilation and/or detoxification. Further experiments are being carried out to clarify PII role in these organisms.