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46  structures 2711  species 2  interactions 11727  sequences 665  architectures

Family: Hpt (PF01627)

Summary: Hpt domain

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Hpt domain Provide feedback

The histidine-containing phosphotransfer (HPt) domain is a novel protein module with an active histidine residue that mediates phosphotransfer reactions in the two-component signaling systems. A multistep phosphorelay involving the HPt domain has been suggested for these signaling pathways. The crystal structure of the HPt domain of the anaerobic sensor kinase ArcB has been determined [1]. The domain consists of six alpha helices containing a four-helix bundle-folding. The pattern of sequence similarity of the HPt domains of ArcB and components in other signaling systems can be interpreted in light of the three-dimensional structure and supports the conclusion that the HPt domains have a common structural motif both in prokaryotes and eukaryotes. In S. cerevisiae ypd1p this domain has been shown to contain a binding surface for Ssk1p (response regulator receiver domain containing protein PF00072) [2].

Literature references

  1. Kato M, Mizuno T, Shimizu T, Hakoshima T; , Cell 1997;88:717-723.: Insights into multistep phosphorelay from the crystal structure of the C-terminal HPt domain of ArcB. PUBMED:9054511 EPMC:9054511

  2. Porter SW, Xu Q, West AH; , Eukaryot Cell 2003;2:27-33.: Ssk1p response regulator binding surface on histidine- containing phosphotransfer protein ypd1p. PUBMED:12582120 EPMC:12582120


External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR008207

Two-component signal transduction systems enable bacteria to sense, respond, and adapt to a wide range of environments, stressors, and growth conditions [PUBMED:16176121]. Some bacteria can contain up to as many as 200 two-component systems that need tight regulation to prevent unwanted cross-talk [PUBMED:18076326]. These pathways have been adapted to response to a wide variety of stimuli, including nutrients, cellular redox state, changes in osmolarity, quorum signals, antibiotics, and more [PUBMED:12372152]. Two-component systems are comprised of a sensor histidine kinase (HK) and its cognate response regulator (RR) [PUBMED:10966457]. The HK catalyses its own auto-phosphorylation followed by the transfer of the phosphoryl group to the receiver domain on RR; phosphorylation of the RR usually activates an attached output domain, which can then effect changes in cellular physiology, often by regulating gene expression. Some HK are bifunctional, catalysing both the phosphorylation and dephosphorylation of their cognate RR. The input stimuli can regulate either the kinase or phosphatase activity of the bifunctional HK.

A variant of the two-component system is the phospho-relay system. Here a hybrid HK auto-phosphorylates and then transfers the phosphoryl group to an internal receiver domain, rather than to a separate RR protein. The phosphoryl group is then shuttled to histidine phosphotransferase (HPT) and subsequently to a terminal RR, which can evoke the desired response [PUBMED:11934609, PUBMED:11489844].

Signal transducing histidine kinases are the key elements in two-component signal transduction systems, which control complex processes such as the initiation of development in microorganisms [PUBMED:8868347, PUBMED:11406410]. Examples of histidine kinases are EnvZ, which plays a central role in osmoregulation [PUBMED:10426948], and CheA, which plays a central role in the chemotaxis system [PUBMED:9989504]. Histidine kinases usually have an N-terminal ligand-binding domain and a C-terminal kinase domain, but other domains may also be present. The kinase domain is responsible for the autophosphorylation of the histidine with ATP, the phosphotransfer from the kinase to an aspartate of the response regulator, and (with bifunctional enzymes) the phosphotransfer from aspartyl phosphate back to ADP or to water [PUBMED:11145881]. The kinase core has a unique fold, distinct from that of the Ser/Thr/Tyr kinase superfamily.

HKs can be roughly divided into two classes: orthodox and hybrid kinases [PUBMED:8029829, PUBMED:1482126]. Most orthodox HKs, typified by the Escherichia coli EnvZ protein, function as periplasmic membrane receptors and have a signal peptide and transmembrane segment(s) that separate the protein into a periplasmic N-terminal sensing domain and a highly conserved cytoplasmic C-terminal kinase core. Members of this family, however, have an integral membrane sensor domain. Not all orthodox kinases are membrane bound, e.g., the nitrogen regulatory kinase NtrB (GlnL) is a soluble cytoplasmic HK [PUBMED:10966457]. Hybrid kinases contain multiple phosphodonor and phosphoacceptor sites and use multi-step phospho-relay schemes instead of promoting a single phosphoryl transfer. In addition to the sensor domain and kinase core, they contain a CheY-like receiver domain and a His-containing phosphotransfer (HPt) domain.

This entry represents a domain present at the N terminus in proteins which undergo autophosphorylation. The group includes, the gliding motility regulatory protein from Myxococcus xanthus and a number of bacterial chemotaxis proteins.

Gene Ontology

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Domain organisation

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Alignments

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

  Seed
(241)
Full
(11727)
Representative proteomes NCBI
(9899)
Meta
(750)
RP15
(1088)
RP35
(2075)
RP55
(2778)
RP75
(3296)
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available

Key: ✓ available, x not generated, not available.

Format an alignment

  Seed
(241)
Full
(11727)
Representative proteomes NCBI
(9899)
Meta
(750)
RP15
(1088)
RP35
(2075)
RP55
(2778)
RP75
(3296)
Alignment:
Format:
Order:
Sequence:
Gaps:
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We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.

  Seed
(241)
Full
(11727)
Representative proteomes NCBI
(9899)
Meta
(750)
RP15
(1088)
RP35
(2075)
RP55
(2778)
RP75
(3296)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download  
Gzipped Download   Download   Download   Download   Download   Download   Download   Download  

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.

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Trees

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Curation and family details

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Curation View help on the curation process

Seed source: Pfam-B_971 (release 4.1)
Previous IDs: none
Type: Family
Author: Bateman A
Number in seed: 241
Number in full: 11727
Average length of the domain: 93.10 aa
Average identity of full alignment: 19 %
Average coverage of the sequence by the domain: 13.09 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 21.8 21.8
Trusted cut-off 21.8 21.8
Noise cut-off 21.7 21.7
Model length: 90
Family (HMM) version: 18
Download: download the raw HMM for this family

Species distribution

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Interactions

There are 2 interactions for this family. More...

Response_reg Hpt

Structures

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Hpt domain has been found. There are 46 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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