2.A.121 The Sulfate Transporter (CysZ) Family The E. coli CysZ protein has a size of 253 aas with 5 TMS. It is a member of the DUF540 or COG2981 protein family. CysZ mutants are deficient in sulfate assimilation and are believed to be defective for sulfate uptake (Britton et al., 1983; Byrne et al., 1988; Parra et al., 1983; Rückert et al., 2005; Aguilar-Barajas et al., 2011). However, a cysZ mutant of Salmonella typhimurium grows normally with 1 mM sulfate (Byrne et al., 1988). Distant homologues of about the same size are found in numerous bacteria, archaea and eukaryotes (e.g., Q6MVD5 in Neurospora crassa and Q08219 in Saccharomyces cerevisiae), and many organisms have multiple CysZ homologues (Marietou et al. 2018). These 5 TMS proteins may be distantly related to 5 TMS uptake proteins of the ABC superfamily. The CysZ homologue in Corynebacterium glutamicum is present in the cysteine biosynthetic operon and was proposed to be a sulphate uptake porter (Rückert et al. 2005). Zhang et al., 2014 reported the purification and functional characterization of the E. coli CysZ protein. Using Isothermal Titration Calorimetry, they observed interactions between CysZ and its substrate, sulfate. CysZ is dedicated to a specific pathway that assimilates sulfate for the synthesis of cysteine. Sulfate uptake via CysZ into E. coli whole cells and proteoliposome was demonstrated, and the cysteine synthesis pathway intermediate, sulfite, interacts directly with CysZ with higher affinity than sulfate. In fact, sulfate transport activity is inhibited by sulfite, suggesting the existence of a feedback inhibition mechanism in which sulfite regulates sulfate uptake by CysZ. Sulfate uptake assays performed at different extracellular pH and in the presence of a proton uncoupler indicated that uptake is driven by the proton gradient (Zhang et al., 2014). The high resolution CysZ structure has been determined (Assur Sanghai et al. 2018), and SO₄^2- binding and flux experiments have provided insight into the molecular mechanism of CysZ-mediated translocation. CysZ structures from three different bacterial species display a previously unknown fold and have subunits organized with inverted transmembrane topology. CysZ from Pseudomonas denitrificans assembles as a trimer of antiparallel dimers and the CysZ structures from two other species recapitulate dimers from this assembly. Mutational studies highlighted the functional relevance of conserved CysZ residues (Assur Sanghai et al. 2018). The transport process catalyzed by CysZ is: H⁺ + SO₄^2- (out) → H⁺ + SO₄^2- (in)
References:
Aguilar-Barajas, E., C. Díaz-Pérez, M.I. Ramírez-Díaz, H. Riveros-Rosas, and C. Cervantes. (2011). Bacterial transport of sulfate, molybdate, and related oxyanions. Biometals 24: 687-707.
Assur Sanghai, Z., Q. Liu, O.B. Clarke, M. Belcher-Dufrisne, P. Wiriyasermkul, M.H. Giese, E. Leal-Pinto, B. Kloss, S. Tabuso, J. Love, M. Punta, S. Banerjee, K.R. Rajashankar, B. Rost, D. Logothetis, M. Quick, W.A. Hendrickson, and F. Mancia. (2018). Structure-based analysis of CysZ-mediated cellular uptake of sulfate. Elife 7:.
Bahk, Y.Y., J. Lee, I.H. Cho, and H.W. Lee. (2010). An analysis of an interactome for apoptosis factor, Ei24/PIG8, using the inducible expression system and shotgun proteomics. J Proteome Res 9: 5270-5283.
Britton, P., A. Boronat, D.A. Hartley, M.C. Jones-Mortimer, H.L. Kornberg, and F. Parra. (1983). Phosphotransferase-mediated regulation of carbohydrate utilization in Escherichia coli K12: location of the gsr (tgs) and iex (crr) genes by specialized transduction. J Gen Microbiol 129: 349-356.
Byrne, C.R., R.S. Monroe, K.A. Ward, and N.M. Kredich. (1988). DNA sequences of the cysK regions of Salmonella typhimurium and Escherichia coli and linkage of the cysK regions to ptsH. J. Bacteriol. 170: 3150-3157.
Marietou, A., H. Røy, B.B. Jørgensen, and K.U. Kjeldsen. (2018). Sulfate Transporters in Dissimilatory Sulfate Reducing Microorganisms: A Comparative Genomics Analysis. Front Microbiol 9: 309.
Mork, C.N., D.V. Faller, and R.A. Spanjaard. (2007). Loss of putative tumor suppressor EI24/PIG8 confers resistance to etoposide. FEBS Lett. 581: 5440-5444.
Parra, F., P. Britton, C. Castle, M.C. Jones-Mortimer, and H.L. Kornberg. (1983). Two separate genes involved in sulphate transport in Escherichia coli K12. J Gen Microbiol 129: 357-358.
Rückert, C., D.J. Koch, D.A. Rey, A. Albersmeier, S. Mormann, A. Pühler, and J. Kalinowski. (2005). Functional genomics and expression analysis of the Corynebacterium glutamicum fpr2-cysIXHDNYZ gene cluster involved in assimilatory sulphate reduction. BMC Genomics 6: 121.
Rømer, M.U., L. Larsen, H. Offenberg, N. Brünner, and U.A. Lademann. (2008). Plasminogen activator inhibitor 1 protects fibrosarcoma cells from etoposide-induced apoptosis through activation of the PI3K/Akt cell survival pathway. Neoplasia 10: 1083-1091.
Zhang, L., W. Jiang, J. Nan, J. Almqvist, and Y. Huang. (2014). The Escherichia coli CysZ is a pH dependent sulfate transporter that can be inhibited by sulfite. Biochim. Biophys. Acta. 1838: 1809-1816.
Examples:
TC#	Name	Organismal Type	Example
Examples:
TC#	Name	Organismal Type	Example
2.A.121.1.1	*Sulfate transporter, CysZ. Part of the cysteine biosynthetic pathway; allosterically inhibited by the biosynthetic intermediate, sulfite (Zhang et al.* 2014).**	Proteobacteria	*CysZ of E. coli* (POA6J3)**

2.A.121.1.2	CysZ homologue	Actinobacteria	CysZ homologue of Streptomyces coelicolor

2.A.121.1.3	Uncharacterized protein, CysZ homologue.	Proteobacteria	CysZ homologue of Idiomarina loihiensis

2.A.121.1.4	Sulfate uptake porter of 246 aas and 4 or 5 TMSs. CysZ from Pseudomonas denitrificans assembles as a trimer of antiparallel dimers, and the CysZ structures from two other species recapitulate dimers from this assembly. Mutational studies highlighted the functional relevance of conserved CysZ residues (Assur Sanghai et al. 2018).		CysZ of Pseudomonas denitrificans

Examples:
TC#	Name	Organismal Type	Example
2.A.121.2.1	Putative sulfate uptake transporter of 5 TMSs, YAL018c	Fungi	*YAL018c of Saccharomyces cerevisiae* (P31379)**

2.A.121.2.10	Uncharacterized protein of 367 aas and 4 or 5 TMSs		UP of Tremella mesenterica

2.A.121.2.11	Uncharacterized protein of 288 aas and 4 or 5 TMSs		UP of Phlebiopsis gigantea

2.A.121.2.12	Uncharacterized protein of 282 aas and 5 TMSs.		UP of Neolentinus lepideus

2.A.121.2.13	Uncharacterized protein of 345 aas and 5or 6 TMSs.		UP of Mortierella verticillata

2.A.121.2.2	The Rrt8p protein of 342 aas.	Fungi	*Rrt8p of Saccharomyces cerevisiae* (Q08219)**

2.A.121.2.3	Uncharacterized protein of 429 aas and 5 TMSs.	Fungi	*UP of Aspergillus* niger (E2PST1)**

2.A.121.2.4	CysZ homologue	Eukaryotes	CysZ homologue of Fusarium oxysporum

2.A.121.2.5	The YOL047C protein	Yeast	*YOL047C of Saccharomyces cerevisiae* (Q08218)**

2.A.121.2.6	Putative sulfate uptake porter of 288 aas and 4 or 5 TMSs.	Fungi	CysZ homologue of Neurospora crassa

2.A.121.2.7	Uncharacterized protein of 261 aas and 4 or 5 TMSs.		UP of Phytophthora parasitica

2.A.121.2.8	Uncharacterized protein of 226 aas and 4 or 5 TMSs.		UP of Ashbya gossypii (Yeast) (Eremothecium gossypii)

2.A.121.2.9	Uncharacterized protein of 309 aas and 5 TMSs		UP of Pseudomassariella vexata

Examples:
TC#	Name	Organismal Type	Example
2.A.121.3.1	*Etoposide-induced protein 2.4, isoform 1, Ei24, or p53-induced gene 8 protein, PIG8. This protein is a apoptosis/autophagy factor (Rømer et al.* 2008; Bahk et al. 2010).**	Animals	Ei24 or Homo sapiens

2.A.121.3.2	Uncharacterized protein	Choanoflagellida (Eukaryote)	CysZ homologue of Monosiga brevicollis

2.A.121.3.3	Ei24 superfamily homologue	Plants	Ei24 homologue of Arabidopsis thaliana

Examples:
TC#	Name	Organismal Type	Example
2.A.121.4.1	The bacterial 4TMS CysZ homologue	ε-Proteobacteria	*CysZ homologue of Campylobacter coli* (E0QD93)**

2.A.121.4.2	5TMS Hypothetical protein, HP	ε-Proteobacteria	*HP of Helicobacter pylori* (E6S4S3)**

2.A.121.4.3	Unnamed protein	α-Proteobacteria	*Unnamed protein of Bartonella clarridgeiae* (E6YFT5)**

2.A.121.4.4	CysZ homologue	β-Proteobacteria	CysZ homologue of Sideroxydans lithotrophicus

2.A.121.4.5	Uncharacterized protein of 298 aas and 7 TMSs	Proteobacteria	UP of Nautilia profundicola

2.A.121.4.6	Uncharacterized protein of 231 aas and 5 TMSs	Spirochaetes	UP of Leptospira interogans

2.A.121.4.7	Uncharacterized protein of 389 aas and 11 TMSs	Bacteroidetes	UP of Bacteroides clarus

2.A.121.4.8	UP of 279 aas and 8 TMSs		UP of Lokiarchaeum sp. GC14_75