Tat (twin-arginine translocation) pathway signal sequence; Proteins assembled with various cofactors or by means of cytosolic molecular chaperones are poor candidates for translocation across the bacterial inner membrane by the standard general secretory (Sec) pathway. This model describes a family of predicted long, non-Sec signal sequences and signal-anchor sequences (uncleaved signal sequences). All contain an absolutely conserved pair of arginine residues, in a motif approximated by (S/T)-R-R-X-F-L-K, followed by a membrane-spanning hydrophobic region. Members with small amino acid side chains at the -1 and -3 positions from the C-terminus of the model should be predicted to be cleaved as are Sec pathway signal sequences. Members are almost exclusively bacterial, although archaeal sequences are also found. A large fraction of the members of this family may have bound redox-active cofactors. [Protein fate, Protein and peptide secretion and trafficking]

                          10        20
                  ....*....|....*....|....*....
1HFE_S          6 ITRRGFLKVACVTTGAALIGIRMTGKAVA 34
Cdd:TIGR01409   1 LSRRDFLKGAAAAGAAAGLGALLPSPARA 29

Iron hydrogenase small subunit; Many microorganisms, such as methanogenic, acetogenic, nitrogen-fixing, photosynthetic, or sulphate-reducing bacteria, metabolise hydrogen. Hydrogen activation is mediated by a family of enzymes, termed hydrogenases, which either provide these organisms with reducing power from hydrogen oxidation, or act as electron sinks. There are two hydrogenases families that differ functionally from each other: NiFe hydrogenases tend to be more involved in hydrogen oxidation, while Iron-only FeFe (Fe only) hydrogenases in hydrogen production. Fe only hydrogenases show a common core structure, which contains a moiety, deeply buried inside the protein, with an Fe-Fe dinuclear centre, nonproteic bridging, terminal CO and CN- ligands attached to each of the iron atoms, and a dithio moiety, which also bridges the two iron atoms and has been tentatively assigned as a di(thiomethyl)amine. This common core also harbours three [4Fe-4S] iron-sulphur clusters. In FeFe hydrogenases, as in NiFe hydrogenases, the set of iron-sulphur clusters is dispersed regularly between the dinuclear Fe-Fe centre and the molecular surface. These clusters are distant by about 1.2 nm from each other but the [4Fe-4S] cluster closest to the dinuclear centre is covalently bound to one of the iron atoms though a thiolate bridging ligand. The moiety including the dinuclear centre, the thiolate bridging ligand, and the proximal [4Fe-4S] cluster is known as the H-cluster. A channel, lined with hydrophobic amino acid side chains, nearly connects the dinuclear centre and the molecular surface. Furthermore hydrogen-bonded water molecule sites have been identified at the interior and at the surface of the protein. The small subunit is comprised of alternating random coil and alpha helical structures that encompass the large subunit in a novel protein fold.

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|.
1HFE_S          46 RINGVYGADAKFPVRASQDNTQVKALYKSYLEKPLGHKSHDLLHTHWFDKS 96
Cdd:smart00902   2 RAEALYNIDKSLPLRKSHENPAVKKLYEEFLGGPLSHKAHELLHTHYHDRE 52

Tat (twin-arginine translocation) pathway signal sequence; Proteins assembled with various cofactors or by means of cytosolic molecular chaperones are poor candidates for translocation across the bacterial inner membrane by the standard general secretory (Sec) pathway. This model describes a family of predicted long, non-Sec signal sequences and signal-anchor sequences (uncleaved signal sequences). All contain an absolutely conserved pair of arginine residues, in a motif approximated by (S/T)-R-R-X-F-L-K, followed by a membrane-spanning hydrophobic region. Members with small amino acid side chains at the -1 and -3 positions from the C-terminus of the model should be predicted to be cleaved as are Sec pathway signal sequences. Members are almost exclusively bacterial, although archaeal sequences are also found. A large fraction of the members of this family may have bound redox-active cofactors. [Protein fate, Protein and peptide secretion and trafficking]

                          10        20
                  ....*....|....*....|....*....
1HFE_S          6 ITRRGFLKVACVTTGAALIGIRMTGKAVA 34
Cdd:TIGR01409   1 LSRRDFLKGAAAAGAAAGLGALLPSPARA 29

Iron hydrogenase small subunit; Many microorganisms, such as methanogenic, acetogenic, nitrogen-fixing, photosynthetic, or sulphate-reducing bacteria, metabolise hydrogen. Hydrogen activation is mediated by a family of enzymes, termed hydrogenases, which either provide these organisms with reducing power from hydrogen oxidation, or act as electron sinks. There are two hydrogenases families that differ functionally from each other: NiFe hydrogenases tend to be more involved in hydrogen oxidation, while Iron-only FeFe (Fe only) hydrogenases in hydrogen production. Fe only hydrogenases show a common core structure, which contains a moiety, deeply buried inside the protein, with an Fe-Fe dinuclear centre, nonproteic bridging, terminal CO and CN- ligands attached to each of the iron atoms, and a dithio moiety, which also bridges the two iron atoms and has been tentatively assigned as a di(thiomethyl)amine. This common core also harbours three [4Fe-4S] iron-sulphur clusters. In FeFe hydrogenases, as in NiFe hydrogenases, the set of iron-sulphur clusters is dispersed regularly between the dinuclear Fe-Fe centre and the molecular surface. These clusters are distant by about 1.2 nm from each other but the [4Fe-4S] cluster closest to the dinuclear centre is covalently bound to one of the iron atoms though a thiolate bridging ligand. The moiety including the dinuclear centre, the thiolate bridging ligand, and the proximal [4Fe-4S] cluster is known as the H-cluster. A channel, lined with hydrophobic amino acid side chains, nearly connects the dinuclear centre and the molecular surface. Furthermore hydrogen-bonded water molecule sites have been identified at the interior and at the surface of the protein. The small subunit is comprised of alternating random coil and alpha helical structures that encompass the large subunit in a novel protein fold.

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|.
1HFE_S          46 RINGVYGADAKFPVRASQDNTQVKALYKSYLEKPLGHKSHDLLHTHWFDKS 96
Cdd:smart00902   2 RAEALYNIDKSLPLRKSHENPAVKKLYEEFLGGPLSHKAHELLHTHYHDRE 52

Tat (twin-arginine translocation) pathway signal sequence; Proteins assembled with various cofactors or by means of cytosolic molecular chaperones are poor candidates for translocation across the bacterial inner membrane by the standard general secretory (Sec) pathway. This model describes a family of predicted long, non-Sec signal sequences and signal-anchor sequences (uncleaved signal sequences). All contain an absolutely conserved pair of arginine residues, in a motif approximated by (S/T)-R-R-X-F-L-K, followed by a membrane-spanning hydrophobic region. Members with small amino acid side chains at the -1 and -3 positions from the C-terminus of the model should be predicted to be cleaved as are Sec pathway signal sequences. Members are almost exclusively bacterial, although archaeal sequences are also found. A large fraction of the members of this family may have bound redox-active cofactors. [Protein fate, Protein and peptide secretion and trafficking]

                          10        20
                  ....*....|....*....|....*....
1HFE_S          6 ITRRGFLKVACVTTGAALIGIRMTGKAVA 34
Cdd:TIGR01409   1 LSRRDFLKGAAAAGAAAGLGALLPSPARA 29