Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q9UIJ5 (Rec)
 58,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The thymine requirement of the E. coli strain HF 4704 (uvr A-, rec A+) is thermosensitive i.e. these cells require for their growth 2 microng thymine per ml at 37 degrees C but not at 30 degrees C. Such cells when starved for thymine for 3 h at 37 degrees C are capable of sustaining growth of single stranded DNA phage phiX174 without any diminution of burst size under nonpermissive conditions. Thymine starved HF 4704 cells also reactivate UV-irradiated phiX174 by about 3fold. To test if the thymine necessary for phage growth under "thymineless" conditions was supplied by host DNA degradation products, the transfer of 32P label from the host DNA to mature progeny phages was measured by means of sucrose density gradient analysis. It was found that only about 0.7% of 32P of the host DNA was transferred to the progeny phages growing in normal cells whereas the corresponding value was 7.8% in the case of thymine starved cells.
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PMID:Growth and reactivation of single stranded DNA phage phiX174 in E. coli undergoing "thymineless death". 32 76

Thymine starvation of Escherichia coli K-12 results in greatly increased sensitivity to ultraviolet light (UV). Our studies, using isogenic strains carrying rec and uvr mutations, have shown the following. (i) Common to all strains tested is a change from multihit to single-hit kinetics of survival to UV after 60 min of thymine starvation. However, the limiting slope of UV survival curves decreases in the rec(+)uvr(+) strain and changes very little in several rec mutant strains and one uvrB mutant strain. Thus, when either the rec or uvr system is functioning alone, the limiting slopes of the UV survival curves are relatively unaffected by thymine starvation. (ii) Thymine starvation does not significantly inhibit repair processes carried out by either repair system alone; i.e., host cell reactivation of irradiated phage (carried out by the uvr system), excision of thymine dimers (uvr), or X-ray repair (rec). (iii) In a rec(+)uvr(+) strain, repair appears to be a synergistic rather than additive function of the two systems. However, after thymine starvation, repair capacity is reduced to about the sum of the repair capacities of the independent systems. (iv) The kinetics of thymineless death are not changed by rec and uvr mutations. This indicates that the lesions responsible for thymineless death are not repaired by rec or uvr systems. (v) Withholding thymine from thy rec(+)uvr(+) bacteria not undergoing thymineless death has no effect on UV sensitivity. Under these conditions one sees higher than normal UV resistance in the presence or absence of thymine. This is due to increased repair carried out by the uvr system. To explain these results we postulate that thymine starvation does not inhibit either the rec or uvr repair pathway directly. Rather it appears that thymine starvation results in increased UV sensitivity in part by inhibiting a function which normally carries out efficient coordination of rec and uvr pathways.
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PMID:Effect of thymine starvation on deoxyribonucleic acid repair systems of Escherichia coli K-12. 456 35