Evolutionary conserved N-terminal region of human muscle fructose 1,6-bisphosphatase regulates its activity and the interaction with aldolase.

N-terminal residues of muscle fructose 1,6-bisphosphatase (FBPase) are highly conserved among vertebrates. In this article, we present evidence that the conservation is responsible for the unique properties of the muscle FBPase isozyme: high sensitivity to AMP and Ca(2+) inhibition and the high affinity to muscle aldolase, which is a factor desensitizing muscle FBPase toward AMP and Ca(2+). The first N-terminal residue affecting the affinity of muscle FBPase to aldolase is arginine 3.

Glu 69 is essential for the high sensitivity of muscle fructose-1,6-bisphosphatase inhibition by calcium ions.

Muscle fructose-1,6-bisphosphatase (FBPase) is highly sensitive toward inhibition by AMP and calcium ions. In allosteric inhibition by AMP, a loop 52-72 plays a decisive role. This loop is a highly conservative region in muscle and liver FBPases.

Arsenical resistance genes in Saccharomyces douglasii and other yeast species undergo rapid evolution involving genomic rearrangements and duplications.

We have isolated and characterized three adjacent Saccharomyces douglasii genes that share remarkable structural homology (97% amino acid sequence identity) with Saccharomyces cerevisiae ARR1 (ACR1), ARR2 (ACR2) and ARR3 (ACR3) genes involved in arsenical resistance. The ARR2 and ARR3 genes encoding the cytoplasmic arsenate reductase and the plasma membrane arsenite transporter are functionally interchangeable in both yeast species. In contrast, a single copy of S.

Intragenic suppressors that restore the activity of the maturase encoded by the second intron of the Saccharomyces cerevisiae cyt b gene.

The protein encoded by the second intron (bi2) of the mitochondrial cyt b gene from Saccharomyces cerevisiae functions as a maturase promoting intron splicing. This protein belongs to a large family characterized by the presence of two conserved motifs: LAGLIDADG (or P1 and P2). We have isolated and characterized spontaneous revertants from two mis-sense mutations, G85D and H92P (localized in the P1 motif of the bi2-maturase), that have a detrimental effect on intron splicing.

Transcriptional activation of metalloid tolerance genes in Saccharomyces cerevisiae requires the AP-1-like proteins Yap1p and Yap8p.

All organisms are equipped with systems for detoxification of the metalloids arsenic and antimony. Here, we show that two parallel pathways involving the AP-1-like proteins Yap1p and Yap8p are required for acquisition of metalloid tolerance in the budding yeast S. cerevisiae.

Metalloid tolerance based on phytochelatins is not functionally equivalent to the arsenite transporter Acr3p.

Active transport of metalloids by Acr3p and Ycf1p in Saccharomyces cerevisiae and chelation by phytochelatins in Schizosaccharomyces pombe, nematodes, and plants represent distinct strategies of metalloid detoxification. In this report, we present results of functional comparison of both resistance mechanisms. The S.