Peptide Utilization by Amino Acid Auxotrophs of Neurospora crassa

Abstract

The ability of auxotrophs of Neurospora crassa to grow on certain tripeptides, despite the presence of excess competing amino acids, suggests it has an oligopeptide transport system. In general, dipeptides did not support growth except in those instances where extracellular hydrolysis occurred, or where the dipeptide appeared to be accumulated by an uptake system which is sensitive to inhibition by free amino acids. Considerable intracellular peptidase activity toward a large number of peptides was demonstrated, including a number of peptides which could not be utilized for growth. The intracellular peptidase activity was shown to be selective for amino acid composition and sequence (N-terminal or C-terminal) within the peptide; glycine-containing peptides were particularly poor substrates for peptidase activity. Only a small amount of extracellular peptidase activity could be detected.

Size restriction on utilization of peptides by amino acid auxotrophs of Neurospora crassa

“…The third possibility mentioned above was examined by concentrating the medium, using Amicon filtration 14, in which leu-2 had grown. The concentrated fluid was dialyzed overnight against tris(hydroxymethyl)aminomethane-hydrochloride buffer (14) before use in peptidase assays. These assays revealed only a small amount of extracellular peptidase activity.…”

“…Cell-free extracts. The cell-free extracts and peptidase assays were as described previously (14), except that the cells were ground in a mortar with an equal weight of acid-washed sand.…”

Dipeptides as Nitrogen Sources for Drosera rotundifolia in Aseptic Culture

“…Being a carnivorous plant, Drosera rotundifotia might be expected to use dipeptides better. The peptide utilization of some micro-organisms is fairly well known (Simmonds et al 1947, 1951, Payne 1972, Wolfinborger and Marzluf 1974 and active transport of dipeptides has recently been reported in higher plants (Higgins andPayne 1977, Sopanen etal. 1977),…”

Peptide utilization in Pseudomonas aeruginosa: evidence for membrane-associated peptidase

“…To utilize this technique with specific microorgani, it is necessary to identify the abilities and limitations of these specific microbial celLs to both ransport and utilize oligopeptides. Studies on a variety of organisms, including bacteria (2,28,33), fungi (19, 26, 36), and mammals (22), have indicated that some similarities exist between organisms in the general characteristics of peptide trnsport. However, other evidence indicates that some parameters of peptide transport vary from species to species (19).…”

“…RESULTS Growth on methionine-containing peptides and derivatives. The ability of peptides to supply an amino acid auxotroph with a required amino acid has been used successfully to ascertain the ability of various cells to transport and degrade peptides(7,13,19,26,36). We used J. BACTERIOL.MEMBRANE-ASSOCIATED PEPTIDASE IN P. AERUGINOSA…”