The translation machinery and 70 kd heat shock protein cooperate in protein synthesis.

The function of the yeast SSB 70 kd heatshock proteins (hsp70s) was investigated by a variety of approaches. The SSB hsp70s (Ssb1/2p) are associated with translating ribosomes. This association is disrupted by puromycin, suggesting that Ssb1/2p may bind directly to the nascent polypeptide.

Isolation and characterization of extragenic suppressors of mutations in the SSA hsp70 genes of Saccharomyces cerevisiae.

Saccharomyces cerevisiae strains that contain null alleles of two hsp70 genes, SSA1 and SSA2, are temperature sensitive for growth. In this study, extragenic suppressors of ssa1 ssa2 have been isolated. Suppression is due to mutations at nuclear loci designated EXA1, EXA2 and EXA3 for EXtragenic suppressor hsp70 subfamily A.

Shoulder problems in the weekend athlete.

With more competitive and recreational athletic pursuits now being undertaken by an aging population, the painful shoulder is seen frequently in the weekend athlete. Episodic stresses to soft-tissue restraints and musculotendinous units around the shoulder lead to a variety of overused pathologic entities. The two most common shoulder problems in the weekend athlete are irritation, swelling, and mechanical impingement; and tearing of the rotator cuff with traumatic shoulder instability (typically of an anterior direction).

Uncoating of coated vesicles by yeast hsp70 proteins.

The ability of hsp70 isoenzymes from wild-type and mutant yeast strains to uncoat bovine brain coated vesicles was analyzed and compared with that of the brain uncoating ATPase. Results show that, among the four major cytoplasmic isoenzymes produced in wild-type yeast, almost all of the activity is associated with the SSA1 and SSA2 isoenzymes. The SSB1 and SSB2 isoenzymes have almost no uncoating activity and are not found in the clathrin-hsp70 complexes formed during the uncoating reaction.

Heat transfer between two degrees of freedom.

A particularly simple chaotic nonequilibrium open system with two Cartesian degrees of freedom, characterized by two distinct temperatures T(x) and T(y), is introduced. The two temperatures are maintained by Nose-Hoover canonical-ensemble thermostats. Both the equilibrium (no net heat transfer) and nonequilibrium (dissipative) Lyapunov spectra are characterized for this simple system.

Functional analysis of a conserved amino-terminal region of HSP70 by site-directed mutagenesis.

Hsp70 proteins have been highly conserved throughout evolution. As a first step in a structure-function analysis of hsp70, we constructed and analysed the consequences of mutations in a portion of the SSA1 gene, a member of the Saccharomyces cerevisiae HSP70 multigene family, that encodes a nearly invariant region near the amino terminus. Analysis of strains expressing SSA1 proteins with alterations at positions 8, 11 and 15 showed that these conserved residues within this region are critical for normal functioning of the protein.

Transcriptional regulation of a yeast HSP70 gene by heat shock factor and an upstream repression site-binding factor.

SSA1, one of the heat-inducible HSP70 genes in the yeast Saccharomyces cerevisiae, displays a significant basal level of expression under optimal growth conditions. Although multiple sites related to the heat shock element (HSE) consensus sequences are present in the SSA1 promoter region, one of these, HSE2, plays a key role in basal expression. An upstream repression site (URS) located adjacent to HSE2 causes repression of basal expression but has little effect on heat-inducible expression of SSA1.

Scanning electron microscopic study of microaneurysms in the diabetic retina.

We describe the clinical and pathologic appearance of the retinal microcirculation in a patient with a 22-year history of diabetes mellitus. A vascular cast of one eye was prepared and studied with scanning electron microscopy. The three-dimensional views obtained give insight into the pathogenesis of microaneurysms.

Commentary on the Louisiana Cancer and Lung Trust Fund Board.

The Louisiana Cancer and Lung Trust Fund Board is pleased to have an agreement with this Journal to report on the accomplishments achieved in prevention, detection, and treatment of cancer and lung diseases. Several papers in this issue attest to the work being done in these areas.

Effect on mydriasis of modifying the volume of phenylephrine drops.

The cardiovascular effects of topically administered phenylephrine 10% are well known and can be minimised by reducing the concentration of drops administered. By modifying the dimensions of the dropper tip we reduced the volume of the drops administered, and therefore the total dose of phenylephrine, without altering the concentration. No difference in the mydriasis produced by drops of small and normal volume could be detected.

Is hsp70 the cellular thermometer?

Cells respond to an increase in temperature by inducing the synthesis of the heat shock proteins, which are a small set of evolutionarily conserved proteins. We review the evidence leading us to suggest that the free pool of one of these proteins, hsp70, serves as a cellular thermometer that regulates the expression of all heat shock proteins.

The effects of progressive abstinence from alcohol on red blood cell proton NMR relaxation times and water content.

Red blood cell proton relaxation times T1 and T2 were measured in samples from chronic alcoholic patients abstinent for varying periods from 1 week to over 6 months. T1 and T2 were elevated in the early stages of abstinence and declined to the values of controls after 8 weeks. Changes in the water content of the red blood cells and the mean corpuscular volume paralleled these changes but were more closely associated with T2.

Precursor proteins in transit through mitochondrial contact sites interact with hsp70 in the matrix.

We previously reported that hsp70 in the mitochondrial matrix (mt-hsp 70 = Ssclp) is required for import of precursor proteins destined for the matrix or intermembrane space. Here we show that mt-hsp70 is also needed for the import of mitochondrial inner membrane proteins. In particular, the precursor of ADP/ATP carrier that is known not to interact with hsp60 on its assembly pathway requires functional mt-hsp70 for import, suggesting a general role of mt-hsp70 in membrane translocation of precursors.

Requirement for hsp70 in the mitochondrial matrix for translocation and folding of precursor proteins.

By analysis of a temperature-sensitive yeast mutant, a heat-shock protein in the matrix of mitochondria, mitochondrial hsp70 (Ssc1p), is found to be involved both in translocation of nuclear-encoded precursor proteins across the mitochondrial membranes and in (re)folding of imported proteins in the matrix.

Structure and regulation of the SSA4 HSP70 gene of Saccharomyces cerevisiae.

SSA4 is the only one of five heat-inducible HSP70 genes in Saccharomyces cerevisiae whose expression is restricted to conditions of stress. Comparison of the nucleotide sequences of the SSA4 gene with other HSP70 genes indicates that it diverged from its most closely related yeast homologues hundreds of millions of years ago. However, a high degree of identity has been maintained between Ssa4p and other yeast 70-kDa heat-shock proteins at the amino acid level suggesting, in light of its distinct pattern of regulation, that it performs an important function.

A review of the role of 70 kDa heat shock proteins in protein translocation across membranes.

The compartmentalization of essential hsp70 proteins indicates that hsp70s carry out crucial functions in several compartments of the cell. The use of conditional mutants has allowed study of the cellular processes that require hsp70 function. For efficient translocation of proteins across membranes hsp70s are required in the cytoplasm, as well as in the matrix of mitochondria and in the lumen of the endoplasmic reticulum.

Sequence and expression of the Escherichia coli recR locus.

The Escherichia coli RecR protein participates in a recombinational DNA repair process. Its gene is located in a region of chromosome that extends from 502 to 509 kilobases on the physical map and that contains apt, dnaX, orf12-recR, htpG, and adk. Most, if not all, of these are involved in nucleic acid metabolism.

Regulation of a yeast HSP70 gene by a cAMP responsive transcriptional control element.

HSP70 genes exhibit complex regulation in response to stress and a variety of cellular and developmental events. The SSA3 HSP70 gene of Saccharomyces cerevisiae is activated at the transcriptional level under conditions of nutrient limitation. Analysis of deletions revealed that cis-acting DNA sequences present immediately upstream and downstream of the previously identified heat shock elements (UASHS) mediate this regulation.

Transcriptional regulation of SSA3, an HSP70 gene from Saccharomyces cerevisiae.

The SSA3 gene of Saccharomyces cerevisiae, a member of the HSP70 multigene family, is expressed at low levels under optimal growth conditions and is dramatically induced in response to heat shock. Sequences coinciding with two overlapping heat shock elements, located 156 base pairs upstream of the transcribed region, were necessary and sufficient for regulation of heat induction. The SSA3 promoter was also activated in an ssa1ssa2 double-mutant strain.

Molecular and developmental characterization of the heat shock cognate 4 gene of Drosophila melanogaster.

The Drosophila heat shock cognate gene 4 (hsc4), a member of the hsp70 gene family, encodes an abundant protein, hsc70, that is more similar to the constitutively expressed human protein than the Drosophila heat-inducible hsp70. Developmental expression revealed that hsc4 transcripts are enriched in cells active in endocytosis and those undergoing rapid growth and changes in shape.

Self-regulation of 70-kilodalton heat shock proteins in Saccharomyces cerevisiae.

To determine whether the 70-kilodalton heat shock proteins of Saccharomyces cerevisiae play a role in regulating their own synthesis, we studied the effect of overexpressing the SSA1 protein on the activity of the SSA1 5'-regulatory region. The constitutive level of Ssa1p was increased by fusing the SSA1 structural gene to the GAL1 promoter. A reporter vector consisting of an SSA1-lacZ translational fusion was used to assess SSA1 promoter activity.

Identification and characterization of a new Escherichia coli gene that is a dosage-dependent suppressor of a dnaK deletion mutation.

We report the isolation and characterization of a previously unidentified Escherichia coli gene that suppresses the temperature-sensitive growth and filamentation of a dnaK deletion mutant strain. Introduction of a multicopy plasmid carrying this wild-type gene into a dnaK deletion mutant strain rescued the temperature-sensitive growth of the dnaK deletion mutant strain at 40.5 degrees C and the filamentation, fully at 37 degrees C and partially at 40.