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2.A.56.1.3
Na+-dependent (smf-driven) sialic acid (N-acetyl neuraminic acid) transporter, SiaTP (Allen et al., 2005; Severi et al., 2005; Johnston et al., 2008). SiaT is also called SiaQM (Mulligan et al., 2009).  Also transports the related sialic acids, N-glycolylneuraminic acid (Neu5Gc) and 3-keto-3-deoxy-D-glycero-D-galactonononic acid (KDN) (Hopkins et al. 2013). Peter et al. 2024 have proposed that conformational coupling of the sialic acid TRAP transporter HiSiaQM with its substrate binding protein HiSiaP accounts for its energetic features. The SBP can adopt an open- or closed state depending on the presence of substrate. The two transmembrane domains of TRAP transporters form a monomeric elevator whose function is strictly dependent on the presence of a sodium ion gradient (Peter et al. 2024).  cryo-EM structure of the Haemophilus influenzae N-acetylneuraminate TRAP transporter (HiSiaQM) at 2.99 Å resolution (extending to 2.2 Å at the core), revealed new features (Currie et al. 2024). .

Accession Number:P44542
Protein Name:SiaP. AKA Sialic acid-binding periplasmic protein
Length:329
Molecular Weight:36513.00
Species:Haemophilus influenzae (strain ATCC 51907 / DSM 11121 / KW20 / Rd) [71421]
Number of TMSs:1
Location1 / Topology2 / Orientation3: Periplasm1
Substrate sodium(1+), N-glycoloyl-beta-neuraminic acid, N-acetyl-beta-neuraminic acid

Cross database links:

Entrez Gene ID: 951056   
Pfam: PF03480   
KEGG: hin:HI0146   

Gene Ontology

GO:0030288 C:outer membrane-bounded periplasmic space
GO:0008643 P:carbohydrate transport

References (4)

[1] “Whole-genome random sequencing and assembly of Haemophilus influenzae Rd.”  Fleischmann R.D.et.al.   7542800
[2] “Two-dimensional map of the proteome of Haemophilus influenzae.”  Langen H.et.al.   10675023
[3] “Sialic acid transport in Haemophilus influenzae is essential for lipopolysaccharide sialylation and serum resistance and is dependent on a novel tripartite ATP-independent periplasmic transporter.”  Severi E.et.al.   16262798
[4] “Conservation of structure and mechanism in primary and secondary transporters exemplified by SiaP, a sialic acid binding virulence factor from Haemophilus influenzae.”  Mueller A.et.al.   16702222
Structure:
2CEX   2CEY   2V4C   2WX9   2WYK   2WYP   2XA5   2XWI   2XWK   2XWO   [...more]

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MMKLTKLFLA TAISLGVSSA VLAADYDLKF GMNAGTSSNE YKAAEMFAKE VKEKSQGKIE 
61:	ISLYPSSQLG DDRAMLKQLK DGSLDFTFAE SARFQLFYPE AAVFALPYVI SNYNVAQKAL 
121:	FDTEFGKDLI KKMDKDLGVT LLSQAYNGTR QTTSNRAINS IADMKGLKLR VPNAATNLAY 
181:	AKYVGASPTP MAFSEVYLAL QTNAVDGQEN PLAAVQAQKF YEVQKFLAMT NHILNDQLYL 
241:	VSNETYKELP EDLQKVVKDA AENAAKYHTK LFVDGEKDLV TFFEKQGVKI THPDLVPFKE 
301:	SMKPYYAEFV KQTGQKGESA LKQIEAINP