A Symmetric Molecule Produced by Mycobacteria Generates Cell-Length Asymmetry during Cell-Division and Thereby Cell-Length Heterogeneity

Diadenosine polyphosphates, Ap_(2–7)A, which contain two adenosines in a 5′,5′ linkage through phosphodiester bonds involving 2–7 phosphates, regulate diverse cellular functions in all organisms, from bacteria to humans, under normal and stress conditions. We had earlier reported consistent occurrence of <b><u>a</u></b>symmetric <b><u>c</u></b>onstriction during <b><u>d</u></b>ivision (ACD) in 20–30% of dividing mycobacterial cells in culture, irrespective of different growth media, implying exogenous action of some factor of mycobacterial origin. Consistent with this premise, concentrated culture supernatant (CCS), but not the equivalent volume-wise concentrated unused medium, dramatically enhanced the ACD proportion to 70–90%. Mass spectrometry and biochemical analyses of the bioactive fraction from CCS revealed the ACD-effecting factor to be Ap₆A. Synthetic Ap₆A showed a mass spectrometry profile, biochemical characteristics, and bioactivity identical to native Ap₆A in the CCS. Thus, the present work reveals a novel role for Ap₆A in generating cell-length asymmetry during mycobacterial cell-division and thereby cell-length heterogeneity in the population