title: Comparative analysis of MazEF and HicAB toxin-antitoxin systems of the cyanobacterium, Anabaena sp. PCC7120.
abstract: Anabaena PCC7120 has two annotated toxin-antitoxin systems: MazEF and HicAB. Overexpression of either of the toxins severely inhibited the growth of Escherichia coli BL21(plysS)(DE3). Of the two Anabaena toxins, MazF exhibited higher toxicity than HicA as evidenced by (i) 100-fold lower viability upon overexpression of MazF compared to HicA; (ii) complete loss of cell viability within 1 h of induction of MazF expression, as against >103colony forming units mL-1in case of HicA; (iii) inability to maintain the MazF overexpressing plasmid in E. coli cells; and (iv) neutralisation of the toxin was effective at the molar ratio of 1:1.9 for MazF:MazE and 13:1 for HicA:HicB, indicating higher antitoxin requirement for neutralisation of MazF. The growth inhibitory effect of MazF was found to be higher in lag phase cultures compared to mid-logarithmic phase cultures of E. coli, while the reverse was true for HicA. The results suggest possible distinct roles for MazEF and HicAB systems of Anabaena.
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
authors.forename: Akhilesh A
authors.initials: AA
authors.lastname: Potnis
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
authors.forename: Prashanth S
authors.initials: PS
authors.lastname: Raghavan
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.|Department of Botany, Savitribai Phule Pune University, Ganeshkhind, Pune-411007, India.
authors.forename: Ashwini
authors.initials: A
authors.lastname: Shelke
authors.affiliation: Department of Botany, Savitribai Phule Pune University, Ganeshkhind, Pune-411007, India.
authors.forename: T D
authors.initials: TD
authors.lastname: Nikam
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India hemaraj@barc.gov.in.|Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Trombay, Mumbai-400094, India.
authors.forename: Hema
authors.initials: H
authors.lastname: Rajaram
mesh_terms: D017033:Anabaena / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D050296:Microbial Viability; D009876:Operon; D010957:Plasmids; D000075704:Toxin-Antitoxin Systems / Q000235:genetics / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins
keywords: Anabaena; HicA, HicB; MazE; MazF; antitoxin; toxin