The main characteristics of the previously described proline-specific transport mechanism (permease) of Escherichia coli were confirmed in strain c4. The same permease was responsible for entry of a number of proline analogues, including 3,4-dehydroproline, 4-methyleneproline, cis- and trans-4-chloroprolines, thiazolidine-4-carboxylic acid (thioproline) and the lower homologue, azetidine-2-carboxylic acid. These analogues also entered the cells by an exchange reaction between extracellular analogue and previously accumulated intracellular proline. Growth of the parent (c4) strain was inhibited by 3,4-dehydroproline and azetidine-2-carboxylic acid, both of which were incorporated into cellular protein. Several classes of mutants, selected for resistance to either dehydroproline or azetidine, failed to incorporate one or both analogues into protein. Some of these mutants owed their resistance to failure to produce a functional proline permease. At least one strain, resistant to azetidine but not to dehydroproline, possessed an altered permease with little affinity for azetidine-2-carboxylic acid but still capable of transporting proline and 3,4-dehydroproline ; the permease of this strain could no longer promote exchange between intracellular proline and extracellular proline or proline analogues.
CohenG. N.,
MunierR.1959; Effets des analogues structuraux d’amino acides sur la croissance, la synthèse de protéines et la synthèse d’enzymes chez Escherichia coli
. Biochim. biophys. Acta 31:347
GottliebA. A.,
FujitaY.,
UdenfriendS.,
WitkopB.1965; Incorporation of cis- and trans-4-fiuoro-l-prolines into proteins and hydroxylation of the trans isomer during collagen biosynthesis. Biochemistry 4:2507
MunierR.,
CohenG. N.1959; Incorporation d’analogues structuraux d’aminoacides dans les protéines bactériennes au cours de leur synthèse in vivo
. Biochim. biophys. Acta 31:378
NealeS.,
TristramH.1965; Loss of ability to concentrate proline in Escherichia coli : basis of resistance to proline analogues. J. gen. Microbiol 39:vii
SchwartzJ. H.,
MaasW. K.,
SimonE. J.1959; An impaired concentrating mechanism for amino acids in mutants of Escherichia coli resistant to l-canavanine and d-serine. Biochim. biophys. Acta 32:582
ShifrinS.,
AmesB. N.,
Ferroluzzi-AmesG.1966; Effect of the α-hydrazino analogue of histidine on histidine transport and arginine synthesis. J. biol. Chem 241:3424
StreckerH. J.1957; The interconversion of glutamic acid and proline. I. The formation of Δ1-pyrroline-5-carboxylic acid from glutamic acid in Escherichia coli
. J. biol. Chem 225:825