Disease relevance of LYS2

• Unlike the Lys2p from S. cerevisiae and C. albicans, the Sz. pombe Lys1p was active when expressed in E. coli and exhibited significant AAR activity without the addition of CoA or the Sz. pombe Lys7p intron free PPTase [1].

High impact information on LYS2

• An act3 mutation also affects expression of the HIS4 and LYS2 genes; thus, Act3p is not a delta element-specific transcriptional regulator [2].
• Silencing by Sir protein targeting can also be initiated at a telomere-proximal site (ADH4), but is much weaker at an internal chromosomal locus (LYS2) [3].
• Finally, we tested integrations of CEN DNA into the genome and found a toleration of wild-type CEN6 DNA when present 3' of the LYS2 gene [4].
• TEF1 maps on chromosome II close to LYS2 [5].
• Similar results were observed when the accumulation of mutations at frameshift hot spots in the LYS2 gene was analyzed, although mutation of MLH3 did not cause the same extent of affect at every LYS2 frameshift hot spot [6].

Biological context of LYS2

• The sin4 delta mutant also shows phenotypes common to histone and spt mutants, including suppression of delta insertion mutations in the HIS4 and LYS2 promoters, expression of promoters lacking upstream activation sequence elements, and decreased superhelical density of circular DNA molecules [7].
• We have cloned the CIF1 gene by complementation of function and located it in a 2.75 kb SphI-BstEII fragment situated at ca. 18 kb centromere distal of LYS2 and ca. 80 kb centromere proximal of TYR1 on chromosome II [8].
• An open reading frame of 2370 bp was localized between SSN6 and LYS2, which has recently been identified (Schild et al., 1991) to be the RAD16 gene [9].
• A 3.9 kb internal pSC5 fragment hybridized only to the plasmid pSC5, but no homology was observed with LYS2 DNA or the YEp24 vector [10].
• The Sz. pombe Lys1p amino acid sequence showed a high degree of similarity to other fungal Lys2p proteins; however, the Lys7p amino acid sequence showed much less similarity to other bacterial, fungal and animal PPTases representing several phylogenetic groups [1].

Anatomical context of LYS2

• Although the modified tRNA Lys2 was recognized by elongation factor (EF) T, the EFT dependent binding to ribosomes to tRNA Lys2 (CNBr) was markedly decreased [11].

Associations of LYS2 with chemical compounds

• Analysis of PsLYS2 sequence suggests that, similarly to S. cerevisiae LYS2, it codes for a polypeptide having two separate enzymatic activities which reside in different domains of the protein, including an adenylate domain, an acyl-carrier site and a short-chain reductase domain [12].
• The LYS2 mRNA and alpha-aminoadipate reductase activity were repressed to a higher level in YEPD-grown cells than in cells grown in the presence of lysine or minimal medium [13].
• Alpha-aminoadipate reductase (AAR), the signature enzyme for lysine biosynthesis in fungi, catalyses the conversion of alpha-aminoadipate to alpha-aminoadipate-semiadehyde in the presence of ATP and NADPH [1].
• Five enzymes (homocitrate synthase, homoisocitrate dehydrogenase, alpha-aminoadipate aminotransferase, alpha-aminoadipate reductase and saccharopine dehydrogenase) were constitutively derepressed in all lys9 mutants with up to eight-fold higher enzyme levels than in isogenic wild-type cells [14].
• However, the recombinant 150-kDa Lys2p, when incubated with CLD2 extract and CoA, exhibited significant AAR activity compared to that of wild-type C. albicans CAI4 extract [15].

Regulatory relationships of LYS2

• The alpha-aminoadipate reductase activity was repressed in lysine-grown wild-type and Lys5+ transformed cells but not in Lys2+ transformed cells [10].
• Rev7 mutants are markedly deficient with respect to UV-induced reversion of lys2, are slightly sensitive to UV and appear to be in the RAD6 epistasis group for UV survival [16].

Other interactions of LYS2

• Furthermore, spt6 and ssn20 mutations fail to complement each other, and ssn20 mutations suppress solo delta insertion mutations at HIS4 and LYS2 [17].
• Mutations in the SPT5 gene of Saccharomyces cerevisiae were isolated previously as suppressors of delta insertion mutations at HIS4 and LYS2 [18].
• Results from the revertant analysis and in vitro complementation indicated LYS2 and LYS5 as structural genes, each encoding a subunit of this large enzyme [19].
• Levels of these enzymes in lys2, lys14, and lys15 mutants were the same or lower than those in wild-type cells [14].
• The gene ALG1 has been mapped on chromosome II at a distance of 2.1 map units from LYS2 [20].

Analytical, diagnostic and therapeutic context of LYS2

• Mutants were generated in the LYS2 sequence of pCaLYS2SEI by PCR mutagenesis and expressed in E. coli BL21 cells [21].
• Fourth, we showed by a complementation test with an authentic lys2 mutant that the integration had inactivated the chromosomal LYS2 gene [22].
• Sequence alignments indicate the presence of all functional domains required for the activation, adenylation, dehydrogenation and alpha-aminoadipic acid binding in the Lys2p [21].
• The alpha-AAR protein of P. chrysogenum was detected by Western blotting using anti-alpha-AAR antibodies [23].
• Nitrate has a strong negative effect on alpha-AAR formation as shown by immunoblotting studies of alpha-AAR [23].

References