A new member of a family of ATPases is essential for assembly of mitochondrial respiratory chain and ATP synthetase complexes in Saccharomyces cerevisiae

Respiration-defective pet mutants of Saccharomyces cerevisiae, assigned to complementation group G25, are grossly deficient in mitochondrial respiratory and ATPase complexes. This phenotype is usually found in strains impaired in mitochondrial protein synthesis. The G25 mutants, however, synthesize all of the proteins encoded by mitochondrial DNA. The mutants are also able to import and process cytoplasmically derived subunits of these enzymes. These results are most compatible with the idea that the gene defined by G25 mutants (RCA1) codes for a protein essential for the assembly of functional respiratory and ATPase complexes. The RCA1 gene has been cloned by complementation of an rca1 mutant with a yeast genomic library. The sequence of the encoded product shows Rca1 protein to be a new member of a recently described family of ATPases. The Rca1 protein is a mitochondrial membrane protein and is the third known member of this family implicated to function in the biogenesis of mitochondria. The primary structure of Rca1 protein indicates several distinct domains in addition to the common purine nucleotide binding region shared by all members of this protein family. One, located in the amino-terminal half, contains two hydrophobic stretches of sufficient length to span a membrane lipid bilayer.

Cloning of the yeast ATP3 gene coding for the gamma-subunit of F1 and characterization of atp3 mutants

Saccharomyces cerevisiae pet mutants, of complementation group G115, are deficient in mitochondrial ATPase and have properties indicative of defective F1. In this study we show that C287/LU1, a mutant belonging to group G115, is complemented by the yeast nuclear ATP3 gene coding for the gamma-subunit of the mitochondrial F1-ATPase. The amino-terminal sequence of the mature gamma-subunit matches the sequence encoded by ATP3 starting with the 34th amino acid confirming the identity of the gene, and earlier evidence indicating that this F1 component is synthesized as a precursor with a long amino-terminal extension. The properties of the mitochondrial ATPase have been studied in C287/LU1 with an Ala273-->Val substitution in the carboxyl-terminal region of the gamma-subunit and in W303 delta ATP3, a mutant lacking the gamma-subunit as a result of a deletion in ATP3. Both strains have negligible ATPase activity but near normal concentrations of the alpha- and beta-subunits of F1. In W303 delta ATP3, the subunits do not form a stable F1 oligomer nor are they firmly associated with F0. This is not true of C287/LU1, which was found to assemble an F1-F0 complex. These data indicate that the yeast gamma-subunit has dual functions, one in catalysis of ATP hydrolysis/synthesis and the second in assembly/stability of F1.

[Detection of serum antibody of hepatitis C virus in parturients and their newborns]

Detection of serum antibody of hepatitis C virus (anti-HCV) with ELISA kits was performed in 315 parturients and their newborns. The results indicated that some of the infants, born of mothers infected with HCV were also anti-HCV positive, and a high positive rate of abnormal maternal hepato-function harbored a markedly positive rate of anti-HCV both in mother and newborn and bore a positive correlation to the maternal age. These suggest that besides the five routine tests, anti-HCV should better be determined, especially in mothers with abnormal hepato-function. If possible, in such cases HCV-RNA should be examined by using revert nested polymerase chain reaction technique to determine whether a vertical mother-infant transmission exists.

[Discussion on criteria for appraising the endanger threatening rare medicinal plants]

This paper deals with the criteria for appraising the endanger threatening rare medicinal plants. A preliminary evaluating method is presented.

[Sero-epidemiological survey of virus infections in pregnant women of the Changchun district]

ELISA method was used to detect Rubella virus specific IgG in serum for 315 pregnant women. Susceptible cases with negative IgG was found in 8.9% (28/315) and recently infected cases was found in 6.0% (19/315). Serum CMV-IgG was assayed for 476 pregnant women. Forty-two cases (8.8%) were found to be negative. The cord serum CMV-IgM positive rate was 2.3% (6/259). Serum Herpes Simplex virus (HSV) IgG was assayed in 384 pregnant women. The negative rate for Type II virus was 26.8% (103/384) and that for Type II virus was 18.0% (53/295). In the cord serum the HSV-Type II and Type IgM was positive each in one case among 212 newborn babies. The results of this preliminary survey indicate that the sero-immunologic estimation of specific globulin is helpful in early detection of intrauterine infection.

Deuterium nuclear magnetic resonance study of the interaction of branched chain compounds (phytanic acid, phytol) with a phospholipid model membrane

Deuterium nuclear magnetic resonance (2H-NMR) spectra have been determined for 50 wt% aqueous dispersions of 1-palmitoyl(stearoyl)-2-[2H31]palmitoyl-sn-glycero-3-phosphocho lin e (PC-d31) containing 20 mol% of the isoprenoid compounds phytol or phytanic acid over the temperature range -5-55 degrees C. Concentration effects of the isoprenoid compounds are also reported. First moments (M1) and order parameters were calculated from the spectra. 20 Mol% of either branched chain compound causes an approximate 9% increase in the mean order parameter SCD. Significant effects are seen on the PC-d31 phase behavior. 20 Mol% of either branched chain compound causes the gel to liquid crystalline onset temperature (Ts) to drop to 28 degrees C from 38 degrees C for PC-d31 alone, as seen from the temperature dependent M1 values. The melting range ([Tl--Ts]) is congruent to 1.5 degrees C for PC-d31 and congruent to 11 degrees C for PC-d31 containing 20 mol% of the branched chain compounds. This is in direct contrast to their straight chain analogues, hexadecanol and palmitic acid, which have been shown to elevate the phase transition temperature. The isoprenoid compounds cause significant disruption of the gel phase, forcing nearest neighbor phospholipid chains apart. Transverse relaxation times (T2e, the time constant for decay of the quandrupolar echo) have been determined over the temperature range -5-50 degrees C. Possible explanation for the effect of the isoprenoid compounds on the dynamic structure of phospholipids in the bilayer are proffered.