>cd02974 AhpF_NTD_N Alkyl hydroperoxide reductase F subunit (AhpF) N-terminal domain (NTD) family, N-terminal TRX-fold subdomain; AhpF is a homodimeric flavoenzyme which catalyzes the NADH-dependent reduction of the peroxiredoxin AhpC, which in turn catalyzes the reduction of hydrogen peroxide and organic hydroperoxides. AhpF contains an NTD forming two contiguous TRX-fold subdomain similar to Pyrococcus furiosus protein disulfide oxidoreductase (PfPDO). It also contains a catalytic core similar to TRX reductase containing FAD and NADH binding domains with an active site disulfide. The proposed mechanism of action of AhpF is similar to a TRX/TRX reductase system. The flow of reducing equivalents goes from NADH - catalytic core of AhpF - NTD of AhpF - AhpC - peroxide substrates. The N-terminal TRX-fold subdomain of AhpF NTD is redox inactive, but is proposed to contain an important residue that aids in the catalytic function of the redox-active CXXC motif contained in the C-terminal TRX-

Probab=93.15 E-value=0.78 Score=25.95 Aligned_cols=76 Identities=16% Similarity=0.242 Sum_probs=59.1 Q ss_pred CCCEEEEEECCCCHHHHHHHHHHHHHHHHCCCCCCCCCCCCCCCHHHHHHHCCCCCCEEEEEECCEEEEEEECCCCCHHH Q ss_conf 99499998769970222134666654210001233322672326577776231568879999799898588748999899 Q gi|254780822|r 19 SNPVVVDFWASWCRPCVKLSPIIDDIADELADKVKITKLDIEESSEISTRYQISSIPTLILFKDGKVIDRMMPGASSQSD 98 (107) Q Consensus 19 ~~~vlv~f~a~wC~~C~~~~p~~~~l~~~~~~~i~~~~vd~d~~~~l~~~~~v~~~Pt~~~~~~g~~~~~~~~g~~~~~~ 98 (107) T Consensus 18 ~~~V~l~~~~~~~~~s~el~~~l~eiasl-SdkI~~~~~~~~-----------~~~Psf~i~~~g~~tgI~F~GIP~GHE 85 (94) T cd02974 18 ENPVELVASLDDSEKSAELLELLEEIASL-SDKITLEEDNDD-----------ERKPSFSINRPGEDTGIRFAGIPMGHE 85 (94) T ss_pred CCCEEEEEEECCCHHHHHHHHHHHHHHHH-CCCEEEEECCCC-----------CCCCEEEEECCCCCCCEEEEECCCCCH T ss_conf 89889999948972169999999999962-895799985798-----------888789994599886669973688601 Q ss_pred HHHHHHHC Q ss_conf 99999841 Q gi|254780822|r 99 IIEWILSR 106 (107) Q Consensus 99 l~~~i~~~ 106 (107) T Consensus 86 F~SliLAl 93 (94) T cd02974 86 FTSLVLAL 93 (94) T ss_pred HHHHHHHH T ss_conf 88999976

HHsearch alignment for GI: 254780822 and conserved domain: cd02974