STRUCTURAL AND FUNCTIONAL ANALYSIS OF THE MAL LOCI OF SACCHAROMYCES.
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Title
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STRUCTURAL AND FUNCTIONAL ANALYSIS OF THE MAL LOCI OF SACCHAROMYCES.
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Identifier
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AAI8801689
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identifier
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8801689
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Creator
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CHARRON, MAUREEN JOAN.
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Contributor
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Corinne A. Michels
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Molecular
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Abstract
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Maltose fermentation by the Saccharomyces yeasts requires the presence of any one of five dominant multigene complexes (MAL1, MAL2, MAL3, MAL4 and MAL6) each of which encodes maltose permease (GENE 1), maltase (GENE 2) and the trans-acting MAL-activator (GENE 3). Four of these loci have been mapped (MAL1-MAL4 and each is located at or near the telomeres of a different chromosome.;Using molecular cloning techniques each of the MAL loci were isolated. I describe the physical structure of the MAL loci and their flanking sequences. The MAL loci were shown to be both structurally and functionally homologous throughout an approximately 9.0 kb region. The orientation of the MAL loci was determined to be: CENTROMERE {dollar}\dots{dollar} GENE 3 - GENE 1 - GENE 2 {dollar}\dots{dollar} TELOMERE. Telomere-adjacent sequences were found flanking GENE 2 of the MAL1, MAL3 and MAL6 loci. No common repeated elements were found on the centromere-proximal side of all of the MAL loci. These results suggest that the MAL loci translocated to different chromosomes via a mechanism that involved the rearrangement(s) of chromosome termini.;In addition to the dominant MAL loci, several partially functional alleles have been identified which are linked to the MAL1 and MAL3 loci. Four naturally occurring alleles of MAL1 have been characterized (MAL1, MAL1p, MAL1g, mal1{dollar}\sp0{dollar}). MAL1 encodes all three genes needed for fermentation. The MAL1p allele functionally encodes only the MAL activator; the MAL1g allele functionally encodes a maltose permease and maltase; and the mal1{dollar}\sp0{dollar} allele functionally encodes only maltase. Molecular analysis of these alleles and several kilobasepairs of flanking sequences indicates that MAL1p, MAL1g and mal1{dollar}\sp0{dollar} have evolved from MAL1 by a series of rearrangements and/or deletions of this telomere-associated locus. I also describe the structure of a unique maltose transport gene contained within MAL1g.;Two alleles of MAL3 have been identified in yeast (MAL3, MAL3g). Similar analysis of these alleles has revealed that MAL3g is structurally and functionally homologous to MAL3 and MAL6 throughout a 6.3 kb region which contains the structural genes for maltase and permease. Analysis of flanking sequences demonstrates that MAL3g evolved from MAL3 via chromosomal rearrangement(s).;Additively, these results emphasize the high degree of fluidity of telomere-adjacent sequences.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biology
