@article {1192, title = {Automation aided optimization of cloning, expression and purification of enzymes of the bacterial sialic acid catabolic and sialylation pathways enzymes for structural studies.}, journal = {Microb Biotechnol}, volume = {11}, year = {2018}, month = {2018 Mar}, pages = {420-428}, abstract = {

The process of obtaining a well-expressing, soluble and correctly folded constructs can be made easier and quicker by automating the optimization of cloning, expression and purification. While there are many semiautomated pipelines available for cloning, expression and purification, there is hardly any pipeline that involves complete automation. Here, we achieve complete automation of all the steps involved in cloning and in\ vivo expression screening. This is demonstrated using 18 genes involved in sialic acid catabolism and the surface sialylation pathway. Our main objective was to clone these genes into a His-tagged Gateway vector, followed by their small-scale expression optimization in\ vivo. The constructs that showed best soluble expression were then selected for purification studies and scaled up for crystallization studies. Our technique allowed us to quickly find conditions for producing significant quantities of soluble proteins in Escherichia coli, their large-scale purification and successful crystallization of a number of these proteins. The method can be implemented in other cases where one needs to screen a large number of constructs, clones and expression vectors for successful recombinant production of functional proteins.

}, issn = {1751-7915}, doi = {10.1111/1751-7915.13041}, author = {Bairy, Sneha and Gopalan, Lakshmi Narayanan and Setty, Thanuja Gangi and Srinivasachari, Sathya and Manjunath, Lavanyaa and Kumar, Jay Prakash and Guntupalli, Sai R and Bose, Sucharita and Nayak, Vinod and Ghosh, Swagatha and Sathyanarayanan, Nitish and Caing-Carlsson, Rhawnie and Wahlgren, Weixiao Yuan and Friemann, Rosmarie and Ramaswamy, S and Neerathilingam, Muniasamy} } @article {1147, title = {Substrate-bound outward-open structure of a Na-coupled sialic acid symporter reveals a new Na site.}, journal = {Nat Commun}, volume = {9}, year = {2018}, month = {2018 May 01}, pages = {1753}, abstract = {

Many pathogenic bacteria utilise sialic acids as an energy source or use them as an external coating to evade immune detection. As such, bacteria that colonise sialylated environments deploy specific transporters to mediate import of scavenged sialic acids. Here, we report a substrate-bound 1.95 {\r A} resolution structure and subsequent characterisation of SiaT, a sialic acid transporter from Proteus mirabilis. SiaT is a secondary active transporter of the sodium solute symporter (SSS) family, which use Na gradients to drive the uptake of extracellular substrates. SiaT adopts the LeuT-fold and is in an outward-open conformation in complex with the sialic acid N-acetylneuraminic acid and two Na ions. One Na binds to the conserved Na2 site, while the second Na binds to a new position, termed Na3, which is conserved in many SSS family members. Functional and molecular dynamics studies validate the substrate-binding site and demonstrate that both Na sites regulate N-acetylneuraminic acid transport.

}, issn = {2041-1723}, doi = {10.1038/s41467-018-04045-7}, author = {Wahlgren, Weixiao Y and Dunevall, Elin and North, Rachel A and Paz, Aviv and Scalise, Mariafrancesca and Bisignano, Paola and Bengtsson-Palme, Johan and Goyal, Parveen and Claesson, Elin and Caing-Carlsson, Rhawnie and Andersson, Rebecka and Beis, Konstantinos and Nilsson, Ulf J and Farewell, Anne and Pochini, Lorena and Indiveri, Cesare and Grabe, Michael and Dobson, Renwick C J and Abramson, Jeff and Ramaswamy, S and Friemann, Rosmarie} } @article {1185, title = {Crystal structure of N-acetylmannosamine kinase from Fusobacterium nucleatum.}, journal = {Acta Crystallogr F Struct Biol Commun}, volume = {73}, year = {2017}, month = {2017 Jun 01}, pages = {356-362}, abstract = {

Sialic acids comprise a varied group of nine-carbon amino sugars that are widely distributed among mammals and higher metazoans. Some human commensals and bacterial pathogens can scavenge sialic acids from their environment and degrade them for use as a carbon and nitrogen source. The enzyme N-acetylmannosamine kinase (NanK; EC 2.7.1.60) belongs to the transcriptional repressors, uncharacterized open reading frames and sugar kinases (ROK) superfamily. NanK catalyzes the second step of the sialic acid catabolic pathway, transferring a phosphate group from adenosine 5{\textquoteright}-triphosphate to the C6 position of N-acetylmannosamine to generate N-acetylmannosamine 6-phosphate. The structure of NanK from Fusobacterium nucleatum was determined to 2.23 {\r A} resolution by X-ray crystallography. Unlike other NanK enzymes and ROK family members, F. nucleatum NanK does not have a conserved zinc-binding site. In spite of the absence of the zinc-binding site, all of the major structural features of enzymatic activity are conserved.

}, keywords = {Adenosine Triphosphate, Amino Acid Sequence, Bacterial Proteins, Binding Sites, Cloning, Molecular, Crystallography, X-Ray, Escherichia coli, Fusobacterium nucleatum, Gene Expression, Genetic Vectors, Hexosamines, Models, Molecular, Phosphotransferases (Alcohol Group Acceptor), Protein Binding, Protein Conformation, alpha-Helical, Protein Conformation, beta-Strand, Protein Interaction Domains and Motifs, Protein Multimerization, Recombinant Proteins, Sequence Alignment, Sequence Homology, Amino Acid, Substrate Specificity}, issn = {2053-230X}, doi = {10.1107/S2053230X17007439}, author = {Caing-Carlsson, Rhawnie and Goyal, Parveen and Sharma, Amit and Ghosh, Swagatha and Setty, Thanuja Gangi and North, Rachel A and Friemann, Rosmarie and Ramaswamy, S} }