- Effects of Thiamine Pyrophosphate on the Inhibition of Self-splicing of Primary Transcripts of T4 phage Thymidylate Synthase Gene in the Presence of GTP
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Hyun Joo Lee , Sung Joon Ahn , Sook Shin , In Kook Park
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J. Microbiol. 2002;40(2):134-139.
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 Abstract
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Effects of GTP on the inhibition of self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td) by thiamine pyrophosphate and its analogs have been investigated. The order of the inhibitory efficiency for compounds tested was as follows: thiamine pyrophosphate > thiamine mono-phosphate > thiamine. Of all compounds examined, thiamine pyrophosphate was the most potent inhibitor. Increasing GTP concentration in splicing reaction tended to overcome the suppressive effects of self-splicing by thiamine pyrophosphate and its analogs. The inhibition by thiamine pyrophosphate was most sensitized to a higher concentration of GTP. It has been speculated that the key structural features in thiamine pyrophosphate and its analogs responsible for the inhibition of splicing may be a thiamine moiety in which the phosphorylation of 2-hydroxylethyl group on 5-position of thiazolium ring rendered further stimulation of inhibition in self-splicing reaction.
- Suppressive Effects of Divalent Cations on Self-splicing Inhibition by Spectinomycin of Group 1 Intron RNA
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In Kook Park
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J. Microbiol. 1999;37(4):243-247.
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Abstract
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Effects of divalent cations on self-splicing inhibition by the antibiotic spectinomycin of the phage T4 thymidylate synthase intro (td) have been investigated. Ca^2+ ion at 1mM concentration suppressed splicing inhibition of spectinomycin by 10% and 50 uM Co^2+ ion also suppressed splicing inhibition of specinomycin by 10%. Mg^2+ ion at 6 mM concentration decreased splicing inhibition of spectinomycin by 42% while Mn^2+ ion decreased the splicing inhibition by 10%. Zn^2+ ion at 10 uM concentration lowered the splicing inhibition by spectinomycin of 15%. Of all divalent cations tested, Mg^2+ ion was the most effective in suppressing splicing inhibition by specinomycin whereas Ca^2+ ion was the least effective. The results suggest that spectinomycin may interact with specific and functional Mg^2+ -binding sites within intron RNA that lead to a displacement of Mg^2+ essential for catalytic activity.
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