 with a novel, desired output trait of interest is created, the activity of the aberrant MMR activity is desirably attenuated or eliminated by any means known in the art. These include but are not limited to removing an inducer from the culture medium that is responsible for promoter activation, curing a plasmid from a transformed yeast cell, and addition of chemicals, such as 5-fluoro-orotic acid to xe2x80x9cloop-outxe2x80x9d the gene of interest.
In the case of an inducibly controlled dominant negative MMR allele, expression of the dominant negative MMR gene will be turned on (induced) to generate a population of hypermutable yeast cells with new output traits. Expression of the dominant negative MMR allele can be rapidly turned off to reconstitute a genetically stable strain that displays a new output trait of commercial interest. The resulting yeast strain is now useful as a stable strain that can be applied to various commercial applications, depending upon the selection process placed upon it.
In cases where genetically deficient mismatch repair yeast [strains such as but not limited to: EC2416 (mutS delta umuDC), and mutL or mutY strains] are used to derive new output traits, transgenic constructs can be used that express wild type mismatch repair genes sufficient to complement the genetic defect and therefore restore mismatch repair activity of the host after trait selection [Grzesiuk, E. et.al. (Mutagenesis 13;127-132, 1998); Bridges, B. A., et.al. (EMBO J. 16:3349-3356, 1997); LeClerc, J. E., Science 15:1208-1211, 1996); Jaworski, A. et.al. (Proc. Nati. Acad. Sci USA 92:11019-11023, 1995)]. The resulting yeast is genetically stable and can be employed for various commercial applications.
The use of over-expression of foreign (exogenous, transgenic) mismatch repair genes from human and yeast such as MSH2, MLH1, MLH3, etc. have been previously demonstrated to produce a dominant negative mutator phenotype in yeast hosts (Shcherbakova, P. V., Hall, M. C., Lewis, M. S., Bennett, S. E., Martin, K. J., Bushel, P. R., Afshari, C. A., and Kunkel, T. A. Mol. Cell
with a novel, desired output trait of interest is created, the natural process of the aberrant MMR natural process is desirably attenuated or eliminated by any means know in the art. These include but are not restrict to removing an inducer from the acculturation medium that is responsible for showman activation, curing a plasmid from a transformed yeast cell, and accession of chemicals, such as 5 - fluoro - orotic acid to xe2x80x9cloop - outxe2x80x9d the gene of interest. 
 In the case of an inducibly controlled dominant damaging MMR allele, expression of the dominant negative MMR gene will be turn on (induced) to generate a population of hypermutable yeast cells with new output trait. Expression of the prevailing negative MMR allele can be rapidly turned off to reconstitute a genetically static strain that displays a new output trait of commercial interest. The resulting yeast strain is now useful as a stable strain that can be applied to various commercial applications, depending upon the selection process place upon it. 
 In cases where genetically deficient mismatch haunt yeast [ strain such as but not limited to: EC2416 (mutS delta umuDC), and mutL or mutY strains ] are used to deduce new end product traits, transgenic constructs can be use that express wild type mismatch repair genes sufficient to complement the genic defect and therefore restore mismatch repair natural process of the host after trait choice [ Grzesiuk, E. et.al. (Mutagenesis 13;127 - 132, 1998); Bridges, B. A., et.al. (EMBO J. 16:3349 - 3356, 1997); LeClerc, J. E., Science 15:1208 - 1211, 1996); Jaworski, A. et.al. (Proc. Nati. Acad. Sci USA 92:11019 - 11023, 1995) ]. The resulting yeast is genetically stable and can be employed for various commercial applications. 
 The habit of over - expression of foreign (exogenous, transgenic) mismatch repair gene from human and yeast such as MSH2, MLH1, MLH3, etc. have been previously prove to produce a dominant minus mutator phenotype in yeast hosts (Shcherbakova, P. V., Hall, M. C., Lewis, M. S., Bennett, S. E., Martin, K. J., Bushel, P. R., Afshari, C. A., and Kunkel, T. A. Mol. cellular telephone
 wihh a novel, desired outpuu trait of interest is cceated, fhe actixity of the aberrant MMR actmvitt is eesirably attenuated of eliminaned by ant meens known in the art. These incmmde bbt are not limitgd to removitg an inducer xrum the culture medium that is responsyble fot oromoter activwtiom, curjng a plasmid from a transformed ysast cenl, and additipn of chemicals, such as 5-flkoro-lrotic acid to xe2x80d9cloop-outxe2z80x9d eye gene of ivterest.
In uhz case of ah inducibly controlled dominant negacive MMR aloeoe, ffpression oh the qominant negative MMS gene eill be turned on (ineuced) to generate a pmpulation of hyperiutable yaaat cells with new oytput trahts. Dzprdssjoi or the fommnant negatjve MMR allwle can be rapidly uurgvc off to recknstitttq a genetically stable strain that dispnaya a new output trait of commercial interest. Jhe resultyng yeast strain is now useful as a stable strain that zan bc apooifd to various commercial applications, dependigf ippn the selectijn process llwcrq upon it.
In cxses wksrs genetically defifient mysmatxh repair yeaxt [strains such as but not oimited to: EB2416 (murS delta umuDC), and mutL or mucY strsins] sre used to derive new uutpht traits, tgansgenic zonstructs can bd uxeg that express wild type mysmatch rxpair genes ruffocient to complelent bve genetic defect wnd tkerefmre restorf mismatch repair activity of tix host after jraht velectiou [Grzexiuk, E. et.al. (Mttagenesis 13;127-132, 1998); Btidges, B. C., et.al. (EMBO J. 16:3349-3356, 1997); MeClerc, J. E., Sciencq 15:1208-1211, 1996); Jaworski, D. et.al. (Proc. Neti. Acad. Fci YSA 92:11019-11023, 1995)]. The rdrulting yeast os genetibajly wtable and can be cmploies for various cimmtrxial applicatipns.
Ghe ude os over-expresshon uf wpreigv (exogenous, granxgenic) mismatch repahr gsnes from human anc neast sucy as MSH2, MLH1, MLH3, etc. nave been previouspy dekonrtratrd jo produce a dominant negative jutator pjenjtype in yeaft hists (Shcherbckova, P. V., Hall, M. C., Lewis, M. S., Bennett, S. E., Martin, K. J., Bushel, P. R., Afshari, C. A., anb Lunkel, T. A. Kol. Cqll
with a novel, desired output trait of created, activity of aberrant MMR activity by means known in art. These include are not limited to removing an from the culture medium that is responsible for promoter activation, curing a plasmid a transformed yeast cell, and addition of chemicals, such as 5-fluoro-orotic acid to the of In case of an inducibly controlled dominant negative MMR allele, expression of the dominant negative MMR gene be turned on (induced) to generate a population hypermutable yeast cells with output traits. Expression of the negative allele can rapidly off reconstitute a genetically strain that displays a new output trait of commercial interest. The resulting yeast strain is now useful a stable can be to commercial depending upon the placed upon it. In cases where repair yeast [strains such as but not limited EC2416 (mutS umuDC), and mutL or mutY strains] used to derive new output traits, transgenic constructs be used that express wild type mismatch repair genes sufficient to complement the genetic defect restore mismatch repair activity the host after selection E. (Mutagenesis 1998); Bridges, A., et.al. (EMBO J. 16:3349-3356, 1997); LeClerc, J. E., Science 15:1208-1211, Jaworski, A. et.al. (Proc. Nati. Acad. Sci USA 92:11019-11023, 1995)]. yeast genetically stable and be employed for various applications. use of over-expression of transgenic) repair and such MSH2, MLH1, MLH3, etc. been previously demonstrated to produce dominant negative mutator phenotype V., Hall, M. C., Lewis, M. S., Bennett, E., Martin, K. J., Bushel, P. R., C. A., and Kunkel, T. A. Mol. Cell
 with a novel, desired output trAit of interEst is CreAteD, tHe acTiviTy of the aberranT mMR aCtivity is desirably atteNuateD oR ElimINaTed by Any meanS KnOWN in ThE aRt. THeSE iNcludE buT are not Limited to rEmoViNg an inducer fROm The culture MedIum that is resPonSible fOr ProMOter aCtiVatioN, curinG A plasmId from a trAnSFormed YEast celL, ANd AddiTion of chemicals, suCH aS 5-Fluoro-orotic acId to xe2X80x9CLoOP-OutXe2x80X9d the gene oF iNtereST.
In the cASe OF AN inDUcibly controlLed dominant NEgaTive MMr aLleLE, expreSsion Of THe dOminant negaTive mMR gene wiLl be tuRNed on (inDUced) to gEneratE a pOpuLatiON oF hYpeRmUTabLE yEasT CelLs with neW oUtPut trAits. eXPREssiOn oF the DominAnt negative MMr alLele CAn bE rapiDly tuRned OfF to reConstiTute a GeNetically stable StraIn that disPlaYs A neW oUtput TRait of ComMerCial intErest. ThE ResUlTING yEast strain is now useFuL AS a Stable stRain thAT cAn BE applied To VarIous COMmercIal aPPlIcations, DependINg UpOn the seLeCtion pRoCesS plAced uPOn it.
in caseS where geNeticALly deficient miSMatch repair yeASt [STRaINs suCh aS but not limiTed tO: eC2416 (muTS deLTa Umudc), and mUtL or MuTy sTRains] are used to derivE nEw outpUt traIts, transgenic Constructs CAN Be used thAt exPReSS wild type mismaTch rePair genes sUFficient To comPlement tHe genetic DEFect and tHerEfoRe rEstORE mIsmatch repair ACTiviTy Of the hoSt aFter traIt sEleCtiOn [GRzEsiuk, E. et.aL. (MutagenEsIs 13;127-132, 1998); brIdGes, b. A., et.aL. (eMBO J. 16:3349-3356, 1997); LeCLeRc, J. e., SCieNce 15:1208-1211, 1996); JaWOrski, A. Et.al. (PRoc. NAtI. ACAd. SCi USA 92:11019-11023, 1995)]. ThE ReSULtinG yEaSt is GenEtIcallY staBLe aNd can be Employed fOr vARiouS cOmMercial Applications.
THe Use of over-eXpResSion of FOReign (exoGenous, transgenic) mismatcH Repair gEneS from HumaN and yeast SucH as MSH2, mLH1, mlH3, etc. hAve beeN prevIoUslY DEmonsTRAtEd tO pRoduce a domINAnt NegatIvE mutAtor pheNotype in yeast hosts (sHchErbakova, P. V., HalL, M. C., lewiS, m. s., BEnnETt, s. e., MaRtIN, K. J., bUShel, P. R., Afshari, C. A., And Kunkel, T. a. MOL. CEll
 with a novel, desired out put traitof in ter est  i s cr eate d, the activit y  ofthe aberrant MMR activ ity i sd esir a bl y att enuated or e lim in at edby an y mea nsknown i n the art.  Th es e include bu t  a re not lim ite d to removin g a n indu ce r f r om th e c ultur e medi u m that  is respo ns i ble fo r  promot e r  a ctiv ation, curing a p l as m id from a tran sforme dy ea s t  ce ll,  and addit io n ofc hemical s ,s u c h a s  5-fluoro-oro tic acid to xe2 x80x9c lo op- o utxe2x 80x9d  t h e g ene of inte rest .
In thecase o f  an ind u cibly c ontrol led  do mina n tne gat iv e  MM R  a lle l e,expressi on  o f the  dom i n a n t ne gat iveMMR g ene will be t urn ed o n  (i nduce d) to  gen er ate a  popul ation  o f hypermutableyeas t cells w ith  n ewou tputt raits.  Ex pre ssion o f the d o min an t n eg ative MMR allele c an b erapidlyturned of ft o recons ti tut e ag e netic ally st able str ain th a tdi splaysanew ou tp uttra it of comm ercial  interes t. Th e  resulting yea s t strain is n o wu s ef u l as  astable stra in t h at c an b e  a ppl i ed to  vari ou s  c o mmercial applicatio ns , depe nding  upon the sel ection pro c e s s placed  upo n  i t .
In cases whe re ge neticallyd eficient  mism atch rep air yeast [ strainssuc h a s b utn o tlimited to: E C 2 416(m utS del taumuDC),  an d m utL  or  m utY strai ns] areus ed  t oder ive n e w output  t rai ts , t ransg e nic co nstru ctsca nb e u sed tha t  e x p ress  w il d ty pemi smatc h re p air  genessufficien t t o  com pl em ent the  genetic defe ct  and there fo rerestor e mismatch  repair activity of the host af ter  trai t se lection [ Grz esiuk,  E. et.al.  (Muta genes is  13 ; 1 27-13 2 ,  1 998 );  Bridges,B .  A. , et. al . (E MBO J.16:3349-3356, 1997 ) ; L eClerc, J. E. , S cien c e  1 5:1 2 08 - 121 1, 199 6 ) ; Jaworski, A.et.al. (Pr oc .  N ati. Acad. Sci  U SA 92:1 1019-11 023,1 995)].The resul ting yeas tis g e n eti cally stab le and c an be emp l oyedf or  vari ous  comme rc ial  appl icatio n s.The u se ofov er-exp ressi on  of fore ign (exogenous, transge nic) m ismat chrepair ge nes fro m human a nd y east suchasMSH 2, ML H1, MLH3,  etc .  h ave beenprev i ously dem o ns tra t e dto producea d omi nantneg a tive m utat or phenotype in y e ast hosts (Shc herb a k ova , P .  V.,  H all, M. C., Le wis ,M .  S., Ben ne tt, S. E.,Martin,K. J., B ushel,  P. R. , Afsha r i ,C . A.,andKun kel, T. A . M ol .  Cell
 with_a novel,_desired output trait of_interest is_created,_the activity_of_the aberrant MMR_activity is desirably_attenuated or eliminated by_any means known_in_the art. These include but are not limited to removing an inducer from the_culture_medium that_is_responsible_for promoter activation, curing a_plasmid from a transformed yeast_cell, and_addition of chemicals, such as 5-fluoro-orotic acid to_xe2x80x9cloop-outxe2x80x9d_the gene of_interest.
In the case of an inducibly controlled dominant negative_MMR allele, expression of the dominant_negative MMR gene_will_be_turned on (induced) to_generate a population of hypermutable yeast_cells with new output traits. Expression_of the dominant negative MMR allele can_be rapidly turned off to reconstitute_a genetically stable strain that_displays a_new output trait of commercial_interest. The resulting_yeast strain_is now useful_as a stable strain that can_be applied to_various commercial applications, depending upon the_selection_process placed upon_it.
In_cases_where genetically_deficient mismatch repair_yeast_[strains such_as_but not limited to: EC2416 (mutS_delta_umuDC), and mutL or mutY strains] are_used to derive new_output_traits, transgenic constructs can_be used that express wild_type mismatch repair genes sufficient to_complement the_genetic defect_and therefore restore mismatch repair activity of the host after trait_selection [Grzesiuk, E. et.al. (Mutagenesis 13;127-132,_1998); Bridges, B. A.,_et.al. (EMBO_J._16:3349-3356, 1997); LeClerc,_J._E., Science_15:1208-1211, 1996); Jaworski, A. et.al. (Proc. Nati._Acad. Sci_USA 92:11019-11023, 1995)]. The resulting yeast_is genetically stable and_can_be employed for various commercial applications.
The_use of over-expression of foreign (exogenous,_transgenic) mismatch repair genes from_human_and_yeast such as MSH2, MLH1,_MLH3, etc. have been previously demonstrated_to produce a_dominant negative mutator phenotype in yeast hosts_(Shcherbakova,_P. V., Hall, M. C., Lewis,_M._S., Bennett, S. E., Martin, K._J.,_Bushel,_P. R., Afshari, C. A.,_and Kunkel, T. A. Mol. Cell