The University of Hyderabad (UoH) organized a Distinguished Lecture titled “Cellular roles of restriction endonucleases – primitive immune system to programmed cell death” by Professor V. Nagaraja, Jawaharlal Nehru Centre for Advanced Scientific Research & Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore on April 11, 2017 at Auditorium, School of Life Sciences, UoH.

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Prof. Nagaraja while delivering the lecture said that, Restriction endonucleases (REases), from the time of their discovery and until now, are considered as bacterial arsenals against the invading genomes. To do so, they generally recognize and cleave DNA in a site specific fashion. He said that, the star activity detected in many of these enzymes was considered to be manifested either under unusual or non-optimal conditions such as ionic strength, glycerol, higher enzyme concentration etc. With the discovery of highly promiscuous nature in Kpn1, an ‘old’ restriction enzyme, we have begun to ask more questions on evolution and other intracellular roles of these enzymes, he added. The enzyme exhibits promiscuity with respect to DNA binding and cleavage as well as co-factor utilization. Now we know that a number of other enzymes are intrinsically promiscuous. The inherent promiscuity of the enzyme may actuallly be beneficial to the organism in many ways, he further added.

Prof. Nagaraja stressed that one of them is a bacterial strategy to remain in the co-evolutionary ‘arms race’ with the invading genomes. Our experiments demonstrated that having such a promiscuous enzyme in its armoury, the organism is better equipped to degrade invading foreign DNA. He said that, the genome, meanwhile is protected by polyamines, the topological state of the DNA and binding by a variety of nucleoid associated proteins.

Prof. Nagaraja said that, we have considered a new intracellular role for REases, using KpnI as a model. We show that under certain conditions, endonuclease triggered DNA damage leads to cellular apoptosis. Such a programmed cell death (PCD) could be an altruistic behavior of the organism to benefit the survival of rest of the population. We have elucidated the mechanism of REase induced PCD and show that nutrients thus released support bacterial growth. We suggest that such an intracellular role may be more wide spread given the vast diversity and occurrence of REases, said Prof. Nagaraja while concluding the lecture.

Prof. P. Reddanna, Dean, School of Life Sciences welcomed and introduced the speaker while Prof. S. Dayananda, senior faculty at Department of Animal Biology, School of Life Sciences proposed a vote of thanks. Prof. Appa Rao Podile, Vice Chancellor, UoH presided over the lecture which was attended by the faculty, students and the staff.

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