Mutational analysis of putative phosphate- and proton-binding sites in the Saccharomyces cerevisiae Pho84 phosphate:H+ transceptor and its effect on signalling to the PKA and PHO pathways

2012 ◽  
Vol 445 (3) ◽  
pp. 413-422 ◽  
Author(s):  
Dieter R. Samyn ◽  
Lorena Ruiz-Pávon ◽  
Michael R. Andersson ◽  
Yulia Popova ◽  
Johan M. Thevelein ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mutational Analysis ◽  
Three Dimensional ◽  
Physiological Role ◽  
Binding Pocket ◽  
Amino Acid Residues ◽  
Three Dimensional Model ◽  
Sequence Alignments ◽  
Multiple Sequence ◽  
Proton Binding

In Saccharomyces cerevisiae, the Pho84 phosphate transporter acts as the main provider of phosphate to the cell using a proton symport mechanism, but also mediates rapid activation of the PKA (protein kinase A) pathway. These two features led to recognition of Pho84 as a transceptor. Although the physiological role of Pho84 has been studied in depth, the mechanisms underlying the transport and sensor functions are unclear. To obtain more insight into the structure–function relationships of Pho84, we have rationally designed and analysed site-directed mutants. Using a three-dimensional model of Pho84 created on the basis of the GlpT permease, complemented with multiple sequence alignments, we selected Arg168 and Lys492, and Asp178, Asp358 and Glu473 as residues potentially involved in phosphate or proton binding respectively, during transport. We found that Asp358 (helix 7) and Lys492 (helix 11) are critical for the transport function, and might be part of the putative substrate-binding pocket of Pho84. Moreover, we show that alleles mutated in the putative proton-binding site Asp358 are still capable of strongly activating PKA pathway targets, despite their severely reduced transport activity. This indicates that signalling does not require transport and suggests that mutagenesis of amino acid residues involved in binding of the co-transported ion may constitute a promising general approach to separate the transport and signalling functions in transceptors.

scholarly journals Clinical and biochemical description of a novel CYP21A2 gene mutation 962_963insA using a new 3D model for the P450c21 protein

2006 ◽  
Vol 155 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Marco Janner ◽  
Amit V Pandey ◽  
Primus E Mullis ◽  
Christa E Flück
Keyword(s):  
Stop Codon ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Biochemical Tests ◽  
Sequence Alignments ◽  
Multiple Sequence ◽  
Cyp21a2 Gene ◽  
Salt Wasting ◽  
Newborn Girl

Objective: A severely virilized 46, XX newborn girl was referred to our center for evaluation and treatment of congenital adrenal hyperplasia (CAH) because of highly elevated 17α-hydroxyprogesterone levels at newborn screening; biochemical tests confirmed the diagnosis of salt-wasting CAH. Genetic analysis revealed that the girl was compound heterozygote for a previously reported Q318X mutation in exon 8 and a novel insertion of an adenine between nucleotides 962 and 963 in exon 4 of the CYP21A2 gene. This 962_963insA mutation created a frameshift leading to a stop codon at amino acid 161 of the P450c21 protein. Aim and methods: To better understand structure–function relationships of mutant P450c21 proteins, we performed multiple sequence alignments of P450c21 with three mammalian P450s (P450 2C8, 2C9 and 2B4) with known structures as well as with human P450c17. Comparative molecular modeling of human P450c21 was then performed by MODELLER using the X-ray crystal structure of rabbit P450 2B4 as a template. Results: The new three dimensional model of human P450c21 and the sequence alignment were found to be helpful in predicting the role of various amino acids in P450c21, especially those involved in heme binding and interaction with P450 oxidoreductase, the obligate electron donor. Conclusion: Our model will help in analyzing the genotype–phenotype relationship of P450c21 mutations which have not been tested for their functional activity in an in vitro assay.

scholarly journals Cloning, post-translational modifications, heterologous expression and ligand-binding of boar salivary lipocalin

2000 ◽  
Vol 350 (2) ◽  
pp. 369-379 ◽  
Author(s):  
Dietrich LOEBEL ◽  
Andrea SCALONI ◽  
Sara PAOLINI ◽  
Carlo FINI ◽  
Lino FERRARA ◽  
...  
Keyword(s):  
Amino Acid ◽  
Sequence Similarity ◽  
Three Dimensional ◽  
Protein Isoforms ◽  
Cysteine Residues ◽  
Protein Chemistry ◽  
Single Individual ◽  
Amino Acid Residues ◽  
Three Dimensional Model ◽  
Submaxillary Glands

Boar submaxillary glands produce the sex-specific salivary lipocalin (SAL), which binds steroidal sex pheromones as endogenous ligands. The cDNA encoding SAL was cloned and sequenced. From a single individual, two protein isoforms, differing in three amino acid residues, were purified and structurally characterized by a combined Edman degradation/MS approach. These experiments ascertained that the mature polypeptide is composed of 168 amino acid residues, that one of the three putative glycosylation sites is post-translationally modified and the structure of the bound glycosidic moieties. Two of the cysteine residues are paired together in a disulphide bridge, whereas the remaining two occur as free thiols. SAL bears sequence similarity to other lipocalins; on this basis, a three-dimensional model of the protein has been built. A SAL isoform was expressed in Escherichiacoli in good yields. Protein chemistry and CD experiments verified that the recombinant product shows the same redox state at the cysteine residues and that the same conformation is observed as in the natural protein, thus suggesting similar folding. Binding experiments on natural and recombinant SAL were performed with the fluorescent probe 1-aminoanthracene, which was efficiently displaced by the steroidal sex pheromone, as well as by several odorants.

scholarly journals Substrate (aglycone) specificity of human cytosolic beta-glucosidase

2003 ◽  
Vol 373 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Jean-Guy BERRIN ◽  
Mirjam CZJZEK ◽  
Paul A. KROON ◽  
W. Russell MCLAUCHLAN ◽  
Antoine PUIGSERVER ◽  
...  
Keyword(s):  
Structural Model ◽  
Homology Modelling ◽  
Three Dimensional ◽  
Amino Acid Residues ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Mutant Proteins ◽  
Metabolizing Enzyme ◽  
Beta Glucosidase

Human cytosolic β-glucosidase (hCBG) is a xenobiotic-metabolizing enzyme that hydrolyses certain flavonoid glucosides, with specificity depending on the aglycone moiety, the type of sugar and the linkage between them. Based upon the X-ray structure of Zea mays β-glucosidase, we generated a three-dimensional model of hCBG by homology modelling. The enzyme exhibited the (β/α)8-barrel fold characteristic of family 1 β-glucosidases, with structural differences being confined mainly to loop regions. Based on the substrate specificity of the human enzymes, sequence alignment of family 1 enzymes and analysis of the hCBG structural model, we selected and mutated putative substrate (aglycone) binding site residues. Four single mutants (Val168→Tyr, Phe225→Ser, Tyr308→Ala and Tyr308→Phe) were expressed in Pichia pastoris, purified and characterized. All mutant proteins showed a decrease in activity towards a broad range of substrates. The Val168→Tyr mutation did not affect Km on p-nitrophenyl (pNP)-glycosides, but increased Km 5-fold on flavonoid glucosides, providing the first biochemical evidence supporting a role for this residue in aglycone-binding of the substrate, a finding consistent with our three-dimensional model. The Phe225→Ser and Tyr308→Ala mutations, and, to a lesser degree, the Tyr308→Phe mutation, resulted in a drastic decrease in specific activities towards all substrates tested, indicating an important role of those residues in catalysis. Taken together with the three-dimensional model, these mutation studies identified the amino-acid residues in the aglycone-binding subsite of hCBG that are essential for flavonoid glucoside binding and catalysis.

scholarly journals BiRDS - Binding Residue Detection from Protein Sequences using Deep ResNets

2021 ◽  
Author(s):  
Vineeth Chelur ◽  
U. Deva Priyakumar
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Tertiary Structure ◽  
Solvent Accessibility ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Relative Solvent Accessibility ◽  
Single Chain ◽  
Sequence Alignments ◽  
Multiple Sequence

Protein-drug interactions play important roles in many biological processes and therapeutics. Prediction of the active binding site of a protein helps discover and optimise these interactions leading to the design of better ligand molecules. The tertiary structure of a protein determines the binding sites available to the drug molecule. A quick and accurate prediction of the binding site from sequence alone without utilising the three-dimensional structure is challenging. Deep Learning has been used in a variety of biochemical tasks and has been hugely successful. In this paper, a Residual Neural Network (leveraging skip connections) is implemented to predict a protein's most active binding site. An Annotated Database of Druggable Binding Sites from the Protein DataBank, sc-PDB, is used for training the network. Features extracted from the Multiple Sequence Alignments (MSAs) of the protein generated using DeepMSA, such as Position-Specific Scoring Matrix (PSSM), Secondary Structure (SS3), and Relative Solvent Accessibility (RSA), are provided as input to the network. A weighted binary cross-entropy loss function is used to counter the substantial imbalance in the two classes of binding and non-binding residues. The network performs very well on single-chain proteins, providing a pocket that has good interactions with a ligand.

scholarly journals Mutational Analysis of the Hexose Transporter ofPlasmodium falciparumand Development of a Three-dimensional Model

2002 ◽  
Vol 277 (34) ◽  
pp. 30942-30949 ◽  
Author(s):  
Suzanne K. Manning ◽  
Charles Woodrow ◽  
Felipe A. Zuniga ◽  
Pavel Iserovich ◽  
Jorge Fischbarg ◽  
...  
Keyword(s):  
Mutational Analysis ◽  
Three Dimensional ◽  
Hexose Transporter ◽  
Dimensional Model ◽  
Three Dimensional Model

Functional analysis of amino acid residues at the dimerisation interface of KpnI DNA methyltransferase

2006 ◽  
Vol 387 (5) ◽  
pp. 515-523 ◽  
Author(s):  
Shivakumara Bheemanaik ◽  
Janusz M. Bujnicki ◽  
Valakunja Nagaraja ◽  
Desirazu N. Rao
Keyword(s):  
Dna Methyltransferase ◽  
Three Dimensional ◽  
Site Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Three Dimensional Model ◽  
Cofactor Binding ◽  
Protein Fold Recognition ◽  
Fluorescence Measurements ◽  
Complete Disruption

AbstractKpnI DNA-(N6-adenine) methyltransferase (M.KpnI) recognises the sequence 5′-GGTACC-3′ and transfers the methyl group fromS-adenosyl-L-methionine (AdoMet) to the N6 position of the adenine residue in each strand. Earlier studies have shown that M.KpnI exists as a dimer in solution, unlike most other MTases. To address the importance of dimerisation for enzyme function, a three-dimensional model of M.KpnI was obtained based on protein fold-recognition analysis, using the crystal structures of M.RsrI and M.MboIIA as templates. Residues I146, I161 and Y167, the side chains of which are present in the putative dimerisation interface in the model, were targeted for site-directed mutagenesis. Methylation andin vitrorestriction assays showed that the mutant MTases are catalytically inactive. Mutation at the I146 position resulted in complete disruption of the dimer. The replacement of I146 led to drastically reduced DNA and cofactor binding. Substitution of I161 resulted in weakening of the interaction between monomers, leading to both monomeric and dimeric species. Steady-state fluorescence measurements showed that the wild-type KpnI MTase induces structural distortion in bound DNA, while the mutant MTases do not. The results establish that monomeric MTase is catalytically inactive and that dimerisation is an essential event for M.KpnI to catalyse the methyl transfer reaction.

scholarly journals Modelling and mutational analysis of Aspergillus nidulans UreA, a member of the subfamily of urea/H + transporters in fungi and plants

Open Biology ◽  
2014 ◽  
Vol 4 (6) ◽  
pp. 140070 ◽  
Author(s):  
Manuel Sanguinetti ◽  
Sotiris Amillis ◽  
Sergio Pantano ◽  
Claudio Scazzocchio ◽  
Ana Ramón
Keyword(s):  
Amino Acids ◽  
Aspergillus Nidulans ◽  
Vibrio Parahaemolyticus ◽  
Mutational Analysis ◽  
Three Dimensional ◽  
Random Mutagenesis ◽  
Membrane Transporters ◽  
Substrate Selectivity ◽  
Dimensional Model ◽  
Three Dimensional Model

We present the first account of the structure–function relationships of a protein of the subfamily of urea/H + membrane transporters of fungi and plants, using Aspergillus nidulans UreA as a study model. Based on the crystal structures of the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT) and of the Nucleobase-Cation-Symport-1 benzylhydantoin transporter from Microbacterium liquefaciens (Mhp1), we constructed a three-dimensional model of UreA which, combined with site-directed and classical random mutagenesis, led to the identification of amino acids important for UreA function. Our approach allowed us to suggest roles for these residues in the binding, recognition and translocation of urea, and in the sorting of UreA to the membrane. Residues W82, Y106, A110, T133, N275, D286, Y388, Y437 and S446, located in transmembrane helixes 2, 3, 7 and 11, were found to be involved in the binding, recognition and/or translocation of urea and the sorting of UreA to the membrane. Y106, A110, T133 and Y437 seem to play a role in substrate selectivity, while S446 is necessary for proper sorting of UreA to the membrane. Other amino acids identified by random classical mutagenesis (G99, R141, A163, G168 and P639) may be important for the basic transporter's structure, its proper folding or its correct traffic to the membrane.

scholarly journals Discovery of Novel Inhibitors for Nek6 Protein through Homology Model Assisted Structure Based Virtual Screening and Molecular Docking Approaches

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
P. Srinivasan ◽  
P. Chella Perumal ◽  
A. Sudha
Keyword(s):  
Virtual Screening ◽  
Cell Cycle Progression ◽  
Three Dimensional ◽  
Homology Model ◽  
Mitotic Cell ◽  
Binding Pocket ◽  
Dynamics Simulation ◽  
Dimensional Structure ◽  
Amino Acid Residues ◽  
Relationship Of

Nek6 is a member of the NIMA (never in mitosis, gene A)-related serine/threonine kinase family that plays an important role in the initiation of mitotic cell cycle progression. This work is an attempt to emphasize the structural and functional relationship of Nek6 protein based on homology modeling and binding pocket analysis. The three-dimensional structure of Nek6 was constructed by molecular modeling studies and the best model was further assessed by PROCHECK, ProSA, and ERRAT plot in order to analyze the quality and consistency of generated model. The overall quality of computed model showed 87.4% amino acid residues under the favored region. A 3 ns molecular dynamics simulation confirmed that the structure was reliable and stable. Two lead compounds (Binding database ID: 15666, 18602) were retrieved through structure-based virtual screening and induced fit docking approaches as novel Nek6 inhibitors. Hence, we concluded that the potential compounds may act as new leads for Nek6 inhibitors designing.

scholarly journals Contrastive learning on protein embeddings enlightens midnight zone at lightning speed

2021 ◽  
Author(s):  
Michael Heinzinger ◽  
Maria Littmann ◽  
Ian Sillitoe ◽  
Nicola Bordin ◽  
Christine Orengo ◽  
...  
Keyword(s):  
Structure Prediction ◽  
Sequence Similarity ◽  
3D Structure ◽  
Three Dimensional ◽  
Hierarchical Classification ◽  
Language Models ◽  
Sequence Alignments ◽  
Sequence Comparisons ◽  
Multiple Sequence ◽  
3D Structures

Thanks to the recent advances in protein three-dimensional (3D) structure prediction, in particular through AlphaFold 2 and RoseTTAFold, the abundance of protein 3D information will explode over the next year(s). Expert resources based on 3D structures such as SCOP and CATH have been organizing the complex sequence-structure-function relations into a hierarchical classification schema. Experimental structures are leveraged through multiple sequence alignments, or more generally through homology-based inference (HBI) transferring annotations from a protein with experimentally known annotation to a query without annotation. Here, we presented a novel approach that expands the concept of HBI from a low-dimensional sequence-distance lookup to the level of a high-dimensional embedding-based annotation transfer (EAT). Secondly, we introduced a novel solution using single protein sequence representations from protein Language Models (pLMs), so called embeddings (Prose, ESM-1b, ProtBERT, and ProtT5), as input to contrastive learning, by which a new set of embeddings was created that optimized constraints captured by hierarchical classifications of protein 3D structures. These new embeddings (dubbed ProtTucker) clearly improved what was historically referred to as threading or fold recognition. Thereby, the new embeddings enabled the intrusion into the midnight zone of protein comparisons, i.e., the region in which the level of pairwise sequence similarity is akin of random relations and therefore is hard to navigate by HBI methods. Cautious benchmarking showed that ProtTucker reached much further than advanced sequence comparisons without the need to compute alignments allowing it to be orders of magnitude faster. Code is available at https://github.com/Rostlab/EAT .

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