TwoUpstream Activation Sequences Control theExpression oftheXPR2GeneintheYeastYarrowia lipolytica SYLVIEBLANCHINROLAND,*RICARDOROMAN CORDEROOTERO,

Summaryof in vivo footprinting data for the UAS1(A) andUAS2(B) regions. Changesin sensitivity to DMS are indicated; all showninteractions were reproducible. Fulland partialprotections of specificguanines on the upperor lowerstrand are indicatedbysolid and open squares, respectively; hyperreactive sites are marked by arrowheads; ? indicates Gresidues that were weak or even missing in allgenomic laddersobtained (seetext). Sequencesimilarities to knowntranscriptional factor-bindingsites ofS. cerevisiae are underlined.Directrepeated sequences are indicated by dashed lines with arrowheads. All positions are designated relative to the Aofthe translation initiation codon. sionoffragment A on its 3' end (fragmentC) didnot strongly increaseits efficiency. Extensionof fragment A on its 5' end (fragment B) activated expression poorly when present insingle copy, but three adjacent copies of fragment Bin thenativeorientationresultedinlevelsof XPR2-lacZexpressioncomparable to thosemeasuredfromthe