Biomaterial Database

Defective guanine uptake in an 8-azaguanine-resistant mutant of Salmonella typhimurium. 1968

J H Thakar, and G P Kalle

An 8-azaguanine-resistant mutant, azg-11, derived from a guanine auxotroph, gua-1, of Salmonella typhimurium was isolated. This mutant was resistant to the analogue when grown on 2,6-diaminopurine, but showed greater susceptibility than the parent on guanine. Studies with the uptake of radioactive purines revealed that the mutant was defective in a mechanism for incorporation of guanine as well as of xanthine. Initial rates of uptake were determined for guanine at concentrations which were sufficiently low to make permeases limiting. The affinity constant K(m) for the mutant was found to be 2.5 x 10(-4)m; that of the parent was 2.3 x 10(-5)m. Examination of cell-free extracts suggested that the purine nucleotide pyrophosphorylases, responsible for the conversion of free intracellular purines to the corresponding nucleotides, were present and unaltered. The results indicate that the mutant is defective in a mechanism for the active transport for guanine and possibly xanthine.

UI	MeSH Term	Description	Entries
D008967	Molecular Biology	A discipline concerned with studying biological phenomena in terms of the chemical and physical interactions of molecules.	Biochemical Genetics,Biology, Molecular,Genetics, Biochemical,Genetics, Molecular,Molecular Genetics,Biochemical Genetic,Genetic, Biochemical,Genetic, Molecular,Molecular Genetic
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D002247	Carbon Isotopes	Stable carbon atoms that have the same atomic number as the element carbon but differ in atomic weight. C-13 is a stable carbon isotope.	Carbon Isotope,Isotope, Carbon,Isotopes, Carbon
D004352	Drug Resistance, Microbial	The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).	Antibiotic Resistance,Antibiotic Resistance, Microbial,Antimicrobial Resistance, Drug,Antimicrobial Drug Resistance,Antimicrobial Drug Resistances,Antimicrobial Resistances, Drug,Drug Antimicrobial Resistance,Drug Antimicrobial Resistances,Drug Resistances, Microbial,Resistance, Antibiotic,Resistance, Drug Antimicrobial,Resistances, Drug Antimicrobial
D005827	Genetics, Microbial	A subdiscipline of genetics which deals with the genetic mechanisms and processes of microorganisms.	Microbial Genetics,Genetic, Microbial,Microbial Genetic
D006147	Guanine
D000225	Adenine	A purine base and a fundamental unit of ADENINE NUCLEOTIDES.	Vitamin B 4,4, Vitamin B,B 4, Vitamin
D001375	Azaguanine	One of the early purine analogs showing antineoplastic activity. It functions as an antimetabolite and is easily incorporated into ribonucleic acids.	Guanazolo,8-Azaguanine,8 Azaguanine
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D012486	Salmonella typhimurium	A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.	Salmonella typhimurium LT2