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Title: [The first steps of chlorophyll synthesis: RNA involvement and regulation]

Abstract

Glu-tRNA[sup Glu] is synthesized from glutamate and tRNA[sup Glu] by glutamyl-tRNA synthetase (GluRS). Recent work has demonstrated that Glu-tRNA[sup Glu] has dual functions and is a precursor for protein and 5-aminolevulinate (ALA) synthesis. Current data does not provide compelling evidence for the notion that GluRS is regulated by chlorophyll precursors or in concert with the other enzymes of ALA synthesis. We have redefined the C5-pathway as a two-step route to ALA starting with Glu-tRNA[sup Glu]. Only two enzymes, Glu-tRNA reductase (GluTR) and GSA-2,1-amino-mutase (GSA-AM), are specifically involved in ALA synthesis. We have purified these enzymatic activities from Chlamydomonas and demonstrated that the two purified proteins in the presence of their cofactors NADPH and pyridoxal phosphate are sufficient for the in vitro Glu-tRNA [yields] ALA conversion. We have cloned the genes encoding GluTR. The sequences of the GluTR proteins deduced from these genes share highly conserved regions with those of bacterial origin. We havealso cloned and analyzed the gene encoding GSA-AM from Arabidopsis. As in Salmonella typhimurium, there are indications of the existence of an additional pathway for ALA formation in E. coli. To shed light on the recognition of the single tRNA[sup Glu] by the chloroplast enzymes GluTR, GluRS wemore » characterized a chlorophyll-deficient mutant of Euglena having tRNA[sup Glu] with a point mutation in the T[Psi]C-loop. The altered tRNA supports protein but not ALA synthesis.« less

Authors:
Publication Date:
Research Org.:
Yale Univ., New Haven, CT (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
6528189
Report Number(s):
DOE/ER/13734-4
ON: DE93014398
DOE Contract Number:  
FG02-87ER13734
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 14 SOLAR ENERGY; ISOMERASES; FRACTIONATION; NUCLEOTIDE DEHYDROGENASES; DNA-CLONING; ALGAE; ARABIDOPSIS; BIOLOGICAL PATHWAYS; CHLOROPLASTS; ESCHERICHIA COLI; GLUTAMIC ACID; PROGRESS REPORT; TRANSFER RNA; AMINO ACIDS; BACTERIA; CARBOXYLIC ACIDS; CELL CONSTITUENTS; CLONING; DNA HYBRIDIZATION; DOCUMENT TYPES; ENZYMES; HYBRIDIZATION; MAGNOLIOPHYTA; MAGNOLIOPSIDA; MICROORGANISMS; NUCLEIC ACIDS; ORGANIC ACIDS; ORGANIC COMPOUNDS; OXIDOREDUCTASES; PLANTS; PROTEINS; RNA; SEPARATION PROCESSES; 550200* - Biochemistry; 140505 - Solar Energy Conversion- Photochemical, Photobiological, & Thermochemical Conversion- (1980-)

Citation Formats

Soell, D. [The first steps of chlorophyll synthesis: RNA involvement and regulation]. United States: N. p., 1992. Web. doi:10.2172/6528189.
Soell, D. [The first steps of chlorophyll synthesis: RNA involvement and regulation]. United States. doi:10.2172/6528189.
Soell, D. Wed . "[The first steps of chlorophyll synthesis: RNA involvement and regulation]". United States. doi:10.2172/6528189. https://www.osti.gov/servlets/purl/6528189.
@article{osti_6528189,
title = {[The first steps of chlorophyll synthesis: RNA involvement and regulation]},
author = {Soell, D},
abstractNote = {Glu-tRNA[sup Glu] is synthesized from glutamate and tRNA[sup Glu] by glutamyl-tRNA synthetase (GluRS). Recent work has demonstrated that Glu-tRNA[sup Glu] has dual functions and is a precursor for protein and 5-aminolevulinate (ALA) synthesis. Current data does not provide compelling evidence for the notion that GluRS is regulated by chlorophyll precursors or in concert with the other enzymes of ALA synthesis. We have redefined the C5-pathway as a two-step route to ALA starting with Glu-tRNA[sup Glu]. Only two enzymes, Glu-tRNA reductase (GluTR) and GSA-2,1-amino-mutase (GSA-AM), are specifically involved in ALA synthesis. We have purified these enzymatic activities from Chlamydomonas and demonstrated that the two purified proteins in the presence of their cofactors NADPH and pyridoxal phosphate are sufficient for the in vitro Glu-tRNA [yields] ALA conversion. We have cloned the genes encoding GluTR. The sequences of the GluTR proteins deduced from these genes share highly conserved regions with those of bacterial origin. We havealso cloned and analyzed the gene encoding GSA-AM from Arabidopsis. As in Salmonella typhimurium, there are indications of the existence of an additional pathway for ALA formation in E. coli. To shed light on the recognition of the single tRNA[sup Glu] by the chloroplast enzymes GluTR, GluRS we characterized a chlorophyll-deficient mutant of Euglena having tRNA[sup Glu] with a point mutation in the T[Psi]C-loop. The altered tRNA supports protein but not ALA synthesis.},
doi = {10.2172/6528189},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1992},
month = {1}
}