The stringent response and cell cycle arrest in Escherichia coli

Berečić, Branimir (2012) The stringent response and cell cycle arrest in Escherichia coli. Bachelor's thesis, Faculty of Science > Department of Biology.

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The bacterial stringent response, triggered by nutritional deprivation, causes an accumulation of the signaling nucleotides ppGpp and pppGpp. Wild type cells undergo a RelA-dependent arrest after treatment with serin hydroxamage in order to contain an integer number of chromosomes and a replication origin/terminus ratio of 1. The growth rate prior to starvation determines the number of chromosomes after arrest; chromosomal regions corresponding to the origins of replication are segregated, while the termination regions remain colocalized. Nucleoids of these arrested cells are decondensed. If treated with chloramphenicol, they become highly condensed, and treatment with rifampicin and cephalexin causes the chromosomes to segregate at their termination regions. Colony formation is inhibited due to ppGpp accumulation, except in ΔseqA and Δdam mutants. Release from starvation causes rapid nucleoid reorganization, chromosome segregation and replication resumption. Accumulation of nucleotid ppGpp, DNA methilation and SeqA binding are all factors which contribute to initiating complete cell cycle arrest, which in turn affects replication initiation and chromosome segregation.

Item Type: Thesis (Bachelor's thesis)
Supervisor: Ivančić Baće, Ivana
Date: 2012
Number of Pages: 13
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 23 Oct 2014 11:54
Last Modified: 16 Feb 2016 13:59

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