Analysis of seven putative Na⁺/H⁺antiporters ofArthrospira platensisNIES-39 using transcription profiling andIn-silicostudies: an indication towards alkaline pH acclimation

AbstractNa+/H+antiporters mediated pH regulation is one of the known mechanism(s), which advocates a possible role of the antiporters in the alkaline pH tolerance ofArthrospira platensisNIES-39 too. Seven putative Na+/H+antiporters have been reported inA. platensis. We have characterized these seven antiporters, where A1, Q2, L2 and L6 belong to the CPA1 family whereas C5, D5 and O6 belong to CPA2 family through variousIn-silicoanalysis. Conserved domain analysis of these seven putative antiporters indicate the presence of nine different kinds of domains. Out of these nine domains, six domains function as monovalent cation-proton antiporters and two as the universal stress protein (Usp) category. Transcription profile of these seven antiporters was also generated at three different pH and time frames which showed a significant difference in the m-RNA levels at pH 7, 9 and at 11 along with a temporal pattern of the expression profile. TheInsilicoand the real time PCR analysis, put together, suggest the active participation of these seven putative Na+/H+antiporters in alkaline pH homeostasis of this cyanobacterial strain where CPA1 subfamily antiporters play a major role.