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BUD8: THE GENE REQUIRED FOR BIPOLAR BUDDING IN Saccharomyces cerevisiae
Gene Name: BUD8
Systematic Name: YLR353W
GenBank accession number: AAB67749
Gene location: Chromosome XII, Coordinates 834351-836162
Cellular role: Cell polarity, Cell wall maintenance, Differentiation
Amino Acids: 603
1 miqsdednld ssettastsy sgtssvssrl qlrtslffen lngahgnpda etematvaye
61 ttsrgqgfav yinnerfsqi mgastsssss snsssitqfh dtqdnnipsn ttvrptslrr
121 dnedtvplrn vtpsqnaavr peravnspss qrlscaltis tsvlmgedve gspieqehsr
181 vvsslyssla nrgndeskng tpprptsiep nettehsffs yhyddtlepd veeavrltkn
241 ktsnvnfiss tgskgegete devidqyepv neskfiphkl kipekagsik sstsddshsp
301 gapgtsarki kipqspslig nilipshnsd ssnesspkdh ighnneekfs skstrkpsts
361 leeegppigl psipvlrsvs gpskwtktpl rlesgnstks dpfsryeghk tpspltkmnk
421 kknktlpehg qplvlapiks qssesdtgqn siiekparsi rrkqqektdn rkedrhdaen
481 idlearmpiq hidtasihsf dsgqngfrdv ysieniivil lccsivpplf fiigcssrrk
541 lvsdyrlmrl lmnkehraal lqgfiwdvdl rwfrmfclil gaaetvivma giaigfgvgi
Figure 1. Budding yeast.
Permission requested from http://tidepool.st.usm.edu/crswr/buddingyeast.html
Two important processes are necessary for proper development of eukaryotes: polarized growth and division site selection (Sheu et al., 2000, http://www.proteome.com/databases/YPD/reports/BUD8.html). There are several genes involved in these processes in yeast including the BUD8 gene, which is specifically involved in the bud initiation of bipolar budding. Diploid yeast cells take on an ellipsoidal shape and specific division pattern, which is the bipolar budding pattern. A few other genes involved in polarity include SPA2, PEA2, BUD6, and BNI1 (Sheu et al., 2000, http://www.proteome.com/databases/YPD/reports/BUD8.html). The bipolar budding pattern depends on persistant positional signals that mark the division site region and the tip of the distal pole on a newborn daughter cell. (Zahner et al., 1996, http://www.proteome.com/databases/YPD/reports/BUD8.html) BUD8 is highly concentrated on the distal end of the cell and directs the initiation of cell division. (Taheri et al., 2000, http://www.proteome.com/databases/YPD/reports/BUD8.html)
LOCALIZATION AND REGULATION
The BUD8 gene is localized to the distal pole of the growing daughter cell and the mother side of the mother-bud neck in haploid and diploid yeast form cells. Localization is not altered by a null mutation in BUD9 or in nitrogen starvation.(Taheri et al., 2000, http://www.proteome.com/databases/YPD/reports/BUD8.html)
Figure 2. Bi-polar budding cells with "lemon"-shaped mother tips. Permission requested from
A double mutation involving both BUD8 and BUD9 leads to budding almost exclusively from the proximal pole rather than the distal pole. http://genome-www4.stanford.edu/cgi-bin/SGD/locus.pl?sgdid=s0004345 Homozygous BUD8 mutation causes homozygous BUD3 mutant or wild-type mutants to bud unipolarly, with most buds emerging from the proximal pole(Zahner et al., 1996, http://www.proteome.com/databases/YPD/reports/BUD8.html). Homozygous mutants also grow slowly on solid medium at 37 degrees (Zahner et al., 1996, http://www.proteome.com/databases/YPD/reports/BUD8.html). Diploid strains of yeast starved for nitrogen undergo a developmental change from growth as single yeast form cells(YF) to a multicellular form that consits of pseudohyphal filaments (PH) (Mosch, 1997, http://www.proteome.com/databases/YPD/reports/BUD8.html). Null mutation inhibits formation of pseudohyphal filaments completely on nitrogen starvation media, but it does not cause a defect in the ability to form long pseudohyphal cells (Taheri et al., 2000, http://www.proteome.com/databases/YPD/reports/BUD8.html). BUD8 is responsibe for 1/16 of the mutations associated with blocked filamentous growth. (Mosch, 1997, http://www.proteome.com/databases/YPD/reports/BUD8.html) Compared to wild-type, overexpression of the BUD8 gene results in increased frequency of unipolar budding on the distal pole (Taheri et al., 2000, http://www.proteome.com/databases/YPD/reports/BUD8.html). A bud8-1; bud9-1; bud3::TRP1 triple mutant buds unipolarly and with buds that emerge from the proximal pole, which indicates that the bud8-1 mutation epistatic to the bud9-1 mutation. (Zahner et al., 1996, http://www.proteome.com/databases/YPD/reports/BUD8.html) A bud8;bud9 double null mutation results in a random budding pattern in both YF and PH diploid cells. The null mutant is viable, which is indicative of its association with other genes in the budding process.
Figure 3. Features around YLR353W on chromosome XII. Spanning a region 10 kb
left and 10 kb right
(coordinates 824351 to 846162). Light blue bar represents the chromosome you are viewing. Red bars are Watson strand ORFs and blue bars are Crick strand ORFs. Permission requested from
Sheu, Y. J., Barral, Y., and Snyder, M. Polarized growth controls cell shape and bipolar bud site selection in Saccharomyces cerevisiae. Mol Cell Biol 20, 5235-5247 (2000).
Zahner, J. E., Harkins, H. A., and Pringle, J. R. Genetic analysis of the bipolar
pattern of bud site selection in the yeast Saccharomyces cerevisiae. Mol Cell
Biol 16, 1857-70 (1996).
Taheri, N., Kohler, T., Braus, G. H., and Mosch, H. U. Asymmetrically localized
Bud8p and Bud9p proteins control yeast cell polarity and development. Embo Journal
19, 6686-6696 (2000).
Mosch, H. U., and Fink, G. R. Dissection of filamentous growth by transposon
mutagenesis in Saccharomyces cerevisiae. Genetics 145, 671-84 (1997).
http://www.proteome.com/databases/YPD/reports/BUD8.html , accessed September 29, 2001.
http://genome-www4.stanford.edu/cgi-binfrom/SGD/ORFMAP/ORFmap?sgdid=S0004345, accessed September 29, 2001.
http://www3.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=AAB67749.1&form=6&db=p&Dopt=g, accessed September 29, 2001.
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