Search PubMed⌕ Search

Biomedical subjects

L Gorini

Publications and source records attributed to L Gorini.

At least 37 records · Page 2Linked to original sources
PubMed1971

Alteration of a 30S ribosomal protein accompanying the ram mutation in Escherichia coli.

The functional peculiarities of ram mutants correlate with an observed alteration in chromatographic mobility of P4(a), a specific protein of the 30S ribosomal subunit. This finding is supported by ribosomal reconstitution experiments. These facts, together with the known location of the ram mutational site in the vicinity of other 30S genetic determinants, suggest that ram is the structural gene for P4(a). The known contrasting roles of ram and strA in determining translational efficiency require that the function of P4(a) should be explained in relation to P10 (the 30S-subunit protein defined by strA). One consequence of altering P4(a), a key protein in ribosome assembly, might be to change the interaction of P10 with the 30S subunit. The functional interrelationship of P4(a) and P10 is discussed in terms of the possible roles of these two proteins in regulating access of tRNA molecules to the decoding site.

Autoradiography↗
PubMed1971

Mechanism of excretion of a bacterial proteinase: demonstration of two proteolytic enzymes produced by a Sarcina strain (Coccus P).

A Sarcina strain (Coccus P) produces two proteolytic enzymes. One is found only extracellularly, is far more prevalent, and is actively excreted during exponential growth. It is the enzyme responsible for the known strong proteolytic activity of the cultures of this strain. A second protease is, however, produced which remains associated with the intact cells but is released by the protoplasts. The two enzymes appear unrelated in their derivation. Calcium ions play an essential role in preventing autodigestion of the excreted enzyme.

Acetates↗
PubMed1971

Mechanism of excretion of a bacterial proteinase: factors controlling accumulation of the extracellular proteinase of a Sarcina strain (Coccus P).

It has been known that the extracellular proteinase of Coccus P is found only in cultures grown in the presence of Ca(2+). It is now shown that this cation is required neither for synthesis, excretion, or activation of a zymogen nor as a prosthetic factor necessary for enzymatic activity. The only function of Ca(2+) is to stabilize the active structure of the enzyme molecule, presumably by substituting for absence of S-S bridges. In the absence of Ca(2+), the excreted proteinase undergoes rapid autodigestion and, instead of the active protein, its hydrolytic products are accumulated in the culture fluid. In minimal medium and under conditions of enzyme stability [presence of Ca(2+) and Ficoll (Pharmacia)], Coccus P accumulates the proteinase at a gradually reduced speed although the rate of cultural growth remains constant. It is shown that this decline in rate of accumulation is caused by the excreted proteinase itself, possibly acting on its own precursor emerging from the cell in a form susceptible to proteolytic attack and not amenable to Ca(2+) protection. A proteinase precursor is actually demonstrable in a calciumless culture at the onset of the enzyme accumulation which follows Ca(2+) addition. It is suggested that excreted proteins require an unfolded (or incompletely folded) structure to cross the cell envelope.

Animals↗
PubMed1969

The dominance of streptomycin sensitivity re-examined.

Several aspects of the strA phenotype were studied in strains of Escherichia coli diploid in the strA chromosomal region. It was found that alleles causing different levels of interference with amber suppression can complement each other, the less restrictive effects being predominant. The sensitive strA(+) allele determines two responses to streptomycin: a dominant effect consisting of a sudden, complete, but reversible inhibition of growth, and a recessive effect manifested as cell killing. Both restriction of suppression and inhibition of growth reflect ribosomal involvement in translation.

Alleles↗
PubMed1967

Phenotype masking and streptomycin dependence.

In attempting to define the role of ribosomes in the mechanism of streptomycin dependence, a new phenomenon has been discovered. Analysis of this phenomenon-called phenotypic masking-leads to the conclusion that "streptomycin dependent" mutants are actually "drug dependent" because their dependence is equally satisfied by several drugs. These drugs, some of which are totally unrelated chemically, act on the ribosome and induce misreading in vitro and suppression in vivo.

Drug Resistance, Microbial↗
PubMed1966

Suppression.

Explore the source record for details and available documents.

Bacteria↗