>cd04243 AAK_AK-HSDH-like AAK_AK-HSDH-like: Amino Acid Kinase Superfamily (AAK), AK-HSDH-like; this family includes the N-terminal catalytic domain of aspartokinase (AK) of the bifunctional enzyme AK- homoserine dehydrogenase (HSDH). These aspartokinases are found in such bacteria as E. coli (AKI-HSDHI, ThrA and AKII-HSDHII, MetL) and in higher plants (Z. mays AK-HSDH). AK and HSDH are the first and third enzymes in the biosynthetic pathway of the aspartate family of amino acids. AK catalyzes the phosphorylation of Asp to P-aspartyl phosphate. HSDH catalyzes the NADPH-dependent conversion of Asp 3-semialdehyde to homoserine. ThrA and MetL are involved in threonine and methionine biosynthesis, respectively. In E. coli, ThrA is subject to allosteric regulation by the end product L-threonine and the native enzyme is reported to be tetrameric. As with bacteria, plant AK and HSDH are feedback inhibited by pathway end products. Maize AK-HSDH is a Thr-sensitive 180-kD enzyme. Arabidopsis AK-

Probab=98.99 E-value=4.3e-09 Score=70.85 Aligned_cols=109 Identities=29% Similarity=0.364 Sum_probs=81.9 Q ss_pred HHHHCCCEEEECCC-CCCCCCCEECC---CHHHHHHHHHHHHCHHHHHHHCCCCCEEECCC------CCCCCCCHHHHHH Q ss_conf 99977984998574-31787320066---14799999998625113343226763353455------5556338889999 Q 537021.9.peg.3 17 LLIKSGIIPVIAPI-APGYDGATYNI---NADTFAGAIAEKLNVIRLLFLTDVPGVLDKNR------QLISKLSINEART 86 (142) Q Consensus 17 ~lL~~g~iPVi~pi-g~~~~G~~~ni---n~D~~a~~lA~~l~A~kli~ltdv~Gv~d~~~------~~i~~i~~~e~~~ 86 (142) T Consensus 174 ~~~~~~~v~Vv~GFig~~~~G~~ttLGRgGSD~sAaila~~l~A~~v~IwtDV~Gi~taDPr~v~~a~~i~~lsy~EA~E 253 (293) T cd04243 174 LLAEHGKVVVTQGFIASNEDGETTTLGRGGSDYSAALLAALLDAEEVEIWTDVDGVYTADPRKVPDARLLKELSYDEAME 253 (293) T ss_pred HHHCCCCEEEECCCCCCCCCCCEEEECCCHHHHHHHHHHHHCCCCEEEEEECCCCEEECCCCCCCCCEECCCCCHHHHHH T ss_conf 86338959997496612799977872798289999999995699889998378840708998788875648108999999 Q ss_pred HHHCCCCCCCHHHHHHHHHHHHHCCCCEEEEEECCCCCHHHHHHHCCCCCCCEE Q ss_conf 962697678678999999999984998899952578768999996799866345 Q 537021.9.peg.3 87 LIKDGTISGGMIPKIETSIKAIENGVKSVAILDGKKPHSILMEIFTKNGSGTLL 140 (142) Q Consensus 87 l~~~~~~~~gm~~Ki~~a~~a~~~Gv~~v~i~~~~~~~~ll~elft~~g~GT~i 140 (142) T Consensus 254 La~~Ga--kVlHp--~ti~p~~~~~Ip-i~i~nt~~----------p~~~GT~I 292 (293) T cd04243 254 LAYFGA--KVLHP--RTIQPAIRKNIP-IFIKNTFN----------PEAPGTLI 292 (293) T ss_pred HHHCCC--CCCCH--HHHHHHHHCCCC-EEEECCCC----------CCCCCEEE T ss_conf 997796--20599--999999986994-89937999----------89998265

HHsearch alignment for GI: peg_394 and conserved domain: cd04243