178K.Brinkrolfetal./JournalofBiotechnology

149 (2010) 173–182

Fig.1.CoregulationsinthetranscriptionalregulatorynetworkofC.glutamicumATCC13032.Thediagramvisualizesthenumberofregulatoryinteractionsexertedbydetectedtranscriptionregulatorsandthenumberoftargetgenesthatareunderdirecttranscriptionalcontrolbyotherregulatoryproteins(coregulations).Genenamesandidenti ersareusedforlabeling.Thelowerleftpartofthediagramisshowninmoredetailintheseparatepanel.Symbols:blackdiamond,localregulator;blackcircle,masterregulator;blacksquare,globalregulator.

3.Transcriptionalregulationsinvolvedinl-lysineandl-glutamatebiosyntheses

In2006,Ikedaandco-workerspublishedafeworiginalarti-clesrelatedto“genomebreeding”withC.glutamicum,revealingsixkeygenes(lysC,hom,pyc,gnd,mqo,andleuC)thatareimpor-tanttargetsfortherationaldesignofanindustriall-lysineproducer(Hayashietal.,2006a;Ikedaetal.,2006;Mitsuhashietal.,2006).Takingthisgeneticinformationintoaccount,Fig.3showsthatpartoftheTRNofC.glutamicumATCC13032thatisinvolvedintheconversionofthecarbonsourcessucrose,glucoseandfruc-toseintothebiotechnologicallyrelevantproductsl-lysineandl-glutamate.ThispartialnetworkreconstructionrevealedahighcomplexityofregulatoryinteractionsinthecentralmetabolismofC.glutamicumexertedby19transcriptionregulators,includ-ingtenrepressors,sixdualregulators,oneactivator,andtwosigmafactors(inadditiontothehousekeepingsigmafactorSigA).Highlyregulatednodesinthenetworkstructureare

the

Fig.2.MatrixofregulatoryinteractionsamongtranscriptionregulatorsandregulatorygenesinC.glutamicumATCC13032.Eachcolouredboxshowsthedirectionoftheregulatoryinteractionofthetranscriptionregulatorlistedinthecorrespondingrowontheexpressionoftheregulatorygeneshowninthecorrespondingcolumns.Thediagonalofthematrixrepresentsautoregulatoryinteractions.Colourcode:red,repression;green,activation.