>TIGR03351 PhnX-like phosphonatase-like hydrolase. This clade of sequences are the closest homologs to the PhnX enzyme, phosphonoacetaldehyde (Pald) hydrolase (phosphonatase, TIGR01422). This phosphonatase-like enzyme and PhnX itself are members of the haloacid dehalogenase (HAD) superfamily (pfam00702) having a a number of distinctive features that set them apart from typical HAD enzymes. The typical HAD N-terminal motif DxDx(T/V) here is DxAGT and the usual conserved lysine prior to the C-terminal motif is instead an arginine. Also distinctive of phosphonatase, and particular to its bi-catalytic mechanism is a conserved lysine in the variable "cap" domain. This lysine forms a Schiff base with the aldehyde of phosphonoacetaldehyde, providing, through the resulting positive charge, a polarization of the C-P bond necesary for cleavage as well as a route to the initial product of cleavage, an ene-amine. The conservation of these elements in this phosphonatase-like enzyme suggests that the

Probab=99.60 E-value=2.4e-15 Score=120.91 Aligned_cols=111 Identities=14% Similarity=0.153 Sum_probs=74.7 Q ss_pred HHHHHHHHHHHHCCCCE-EECCCCCCCCCCCCHHHHHH-HHHHHHHH-HCCCCCCCCCCCCHHHHHHHHHHHHHHCCCCC Q ss_conf 99999999997305740-31266432256630011048-99998875-04765323477702589999986543148890 Q gi|254780847|r 140 EDYRMLLERFAHRHIPL-ICANPDIVANRGNKIIPCAG-ALALIYQQ-LNGIVKMIGKPHLPIYEMAFKKISSLCNSFNK 216 (282) Q Consensus 140 ~~~~~l~~~~~~~~~~~-i~~N~D~~~p~~~~~~~~~G-~~~~~~~~-~~g~~~~~GKP~~~~~~~a~~~l~~~~~~~~~ 216 (282) T Consensus 90 pG~~elL~~L~~~gi~~av~T~~~~~~~~--~~l~~~g~~~~~~fd~vv~~~dv~~~KP~Pd~~l~a~~~lg~----~~~ 163 (220) T TIGR03351 90 PGAEEAFRSLRSSGIKVALTTGFDRDTAE--RLLEKLGWTVGDDVDAVVCPSDVAAGRPAPDLILRAMELTGV----QDV 163 (220) T ss_pred CCHHHHHHHHHHCCCCEEEECCCCHHHHH--HHHHHHCCCHHHHCCCCCCCCCCCCCCCCHHHHHHHHHHHCC----CCC T ss_conf 11999999999879977663599779999--999982764043224045634356679878999999999588----964 Q ss_pred CCEEEECCCHHHHHHHHHHCCCC-EEEECCCCCCHHHHHHCC Q ss_conf 00899738857889999976996-999718678777842048 Q gi|254780847|r 217 KRILAIGDGMDTDIKGALQSGID-ALYVSDGIHRHEYLFNDN 257 (282) Q Consensus 217 ~~~lmIGD~l~tDI~gA~~~G~~-silV~tG~~~~~~~~~~~ 257 (282) T Consensus 164 ~~~~vigDs~-~di~aA~~AG~~~~igv~~G~~~~~~L~~~g 204 (220) T TIGR03351 164 QSVAVAGDTP-NDLEAGINAGAGAVVGVLTGAHDAEELSRHP 204 (220) T ss_pred CCEEECCCCH-HHHHHHHHCCCCEEEEEECCCCCHHHHHHCC T ss_conf 3313537878-8999999859987999838999999998789

HHsearch alignment for GI: 254780847 and conserved domain: TIGR03351