scholarly journals Structural and functional analysis of tomato sterol C22 desaturase

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Laura Gutiérrez-García ◽  
Montserrat Arró ◽  
Teresa Altabella ◽  
Albert Ferrer ◽  
Albert Boronat
Keyword(s):  
Catalytic Domain ◽  
Transmembrane Domain ◽  
Current Knowledge ◽  
Complex Mixture ◽  
Structural Features ◽  
Structure And Function ◽  
Cell Fractionation ◽  
Globular Domain ◽  
And Function ◽  
Functional Components

Abstract Background Sterols are structural and functional components of eukaryotic cell membranes. Plants produce a complex mixture of sterols, among which β-sitosterol, stigmasterol, campesterol, and cholesterol in some Solanaceae, are the most abundant species. Many reports have shown that the stigmasterol to β-sitosterol ratio changes during plant development and in response to stresses, suggesting that it may play a role in the regulation of these processes. In tomato (Solanum lycopersicum), changes in the stigmasterol to β-sitosterol ratio correlate with the induction of the only gene encoding sterol C22-desaturase (C22DES), the enzyme specifically involved in the conversion of β-sitosterol to stigmasterol. However, despite the biological interest of this enzyme, there is still a lack of knowledge about several relevant aspects related to its structure and function. Results In this study we report the subcellular localization of tomato C22DES in the endoplasmic reticulum (ER) based on confocal fluorescence microscopy and cell fractionation analyses. Modeling studies have also revealed that C22DES consists of two well-differentiated domains: a single N-terminal transmembrane-helix domain (TMH) anchored in the ER-membrane and a globular (or catalytic) domain that is oriented towards the cytosol. Although TMH is sufficient for the targeting and retention of the enzyme in the ER, the globular domain may also interact and be retained in the ER in the absence of the N-terminal transmembrane domain. The observation that a truncated version of C22DES lacking the TMH is enzymatically inactive revealed that the N-terminal membrane domain is essential for enzyme activity. The in silico analysis of the TMH region of plant C22DES revealed several structural features that could be involved in substrate recognition and binding. Conclusions Overall, this study contributes to expand the current knowledge on the structure and function of plant C22DES and to unveil novel aspects related to plant sterol metabolism.

scholarly journals Structural and Functional Analysis of Tomato Sterol C22 Desaturase

2020 ◽  
Author(s):  
Laura Gutiérrez-García ◽  
Montserrat Arró ◽  
Teresa Altabella ◽  
Albert Ferrer ◽  
Albert Boronat
Keyword(s):  
Catalytic Domain ◽  
Transmembrane Domain ◽  
Current Knowledge ◽  
Complex Mixture ◽  
Structural Features ◽  
Structure And Function ◽  
Cell Fractionation ◽  
Globular Domain ◽  
Essential Components ◽  
And Function

Abstract Background: Sterols are essential components of eukaryotic cells that modulate membrane biophysical properties and function. Plants produce a complex mixture of sterols, among which β-sitosterol, stigmasterol, campesterol, and cholesterol in some Solanaceae, are the most abundant species. Many reports have shown that the stigmasterol to β-sitosterol ratio changes during plant development and in response to stresses, suggesting that it may play a role in the regulation of these processes. In tomato (Solanum lycopersicum), changes in the stigmasterol to β-sitosterol ratio correlate with the induction of the only gene encoding sterol C22-desaturase (C22DES), the enzyme specifically involved in the conversion of β-sitosterol to stigmasterol. However, despite the biological interest of this enzyme, there is still a lack of knowledge about several relevant aspects related to its structure and function.Results: In this study we report the subcellular localization of tomato C22DES in the endoplasmic reticulum (ER) based on confocal fluorescence microscopy and cell fractionation analyses. Modeling studies have also revealed that C22DES consists of two well-differentiated domains: a single N-terminal transmembrane-helix domain (TMH) anchored in the ER-membrane and a globular (or catalytic) domain that is oriented towards the cytosol. Although TMH is sufficient for the targeting and retention of the enzyme in the ER, the globular domain may also interact and be retained in the ER in the absence of the N-terminal transmembrane domain. The observation that a truncated version of C22DES lacking the TMH is enzymatically inactive revealed that the N-terminal membrane domain is essential for enzyme activity. The in silico analysis of the TMH region of plant C22DES revealed several structural features that could be involved in substrate recognition and binding.Conclusions: Overall, this study contributes to expand the current knowledge on the structure and function of plant C22DES and to unveil novel aspects related with plant sterol metabolism.

Macromolecular constituents of basement membranes: a review of current knowledge on their structure and function

1983 ◽  
Vol 61 (8) ◽  
pp. 942-948 ◽  
Author(s):  
Paul G. Scott
Keyword(s):  
Type Iv Collagen ◽  
Current Knowledge ◽  
Heparan Sulphate ◽  
Structural Features ◽  
Structure And Function ◽  
Basement Membranes ◽  
Type Iv ◽  
Type V ◽  
And Function ◽  
Additional Form

Macromolecules which appear to be integral constituents of basement membranes include type IV collagen, the glycoprotein laminin, and heparan sulphate proteoglycan. Another glycoprotein, fibronectin, may occupy an intermediate position between some lining cells and their basement membranes but is not, however, restricted to this location. An additional form of collagen, genetic type V which differs significantly from type IV collagen in structure, appears to be associated with some basement membranes, possibly linking them to underlying connective tissue. The main structural features of each of these macromolecules, as presently understood, are reviewed here as a background to the experimental papers in this "mini-symposium."

scholarly journals Structure and Function of the CFTR Chloride Channel

1999 ◽  
Vol 79 (1) ◽  
pp. S23-S45 ◽  
Author(s):  
DAVID N. SHEPPARD ◽  
MICHAEL J. WELSH
Keyword(s):  
Cystic Fibrosis ◽  
Chloride Channel ◽  
Atp Hydrolysis ◽  
Current Knowledge ◽  
Structure And Function ◽  
Binding Domains ◽  
Transporter Family ◽  
Membrane Spanning ◽  
And Function ◽  
R Domain

Sheppard, David N., and Michael J. Welsh. Structure and Function of the CFTR Chloride Channel. Physiol. Rev. 79 , Suppl.: S23–S45, 1999. — The cystic fibrosis transmembrane conductance regulator (CFTR) is a unique member of the ABC transporter family that forms a novel Cl− channel. It is located predominantly in the apical membrane of epithelia where it mediates transepithelial salt and liquid movement. Dysfunction of CFTR causes the genetic disease cystic fibrosis. The CFTR is composed of five domains: two membrane-spanning domains (MSDs), two nucleotide-binding domains (NBDs), and a regulatory (R) domain. Here we review the structure and function of this unique channel, with a focus on how the various domains contribute to channel function. The MSDs form the channel pore, phosphorylation of the R domain determines channel activity, and ATP hydrolysis by the NBDs controls channel gating. Current knowledge of CFTR structure and function may help us understand better its mechanism of action, its role in electrolyte transport, its dysfunction in cystic fibrosis, and its relationship to other ABC transporters.

scholarly journals Cysteine-Free Proteins in the Immunobiology of Arthropod-Borne Diseases

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
J. Santiago Mejia ◽  
Erik N. Arthun ◽  
Richard G. Titus
Keyword(s):  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Distribution Patterns ◽  
Structural Features ◽  
Structure And Function ◽  
Cysteine Residues ◽  
Distribution Analysis ◽  
And Function ◽  
Abundance And Distribution ◽  
Host Parasite

One approach to identify epitopes that could be used in the design of vaccines to control several arthropod-borne diseases simultaneously is to look for common structural features in the secretome of the pathogens that cause them. Using a novel bioinformatics technique, cysteine-abundance and distribution analysis, we found that many different proteins secreted by several arthropod-borne pathogens, includingPlasmodium falciparum, Borrelia burgdorferi, and eight species of Proteobacteria, are devoid of cysteine residues. The identification of three cysteine-abundance and distribution patterns in several families of proteins secreted by pathogenic and nonpathogenic Proteobacteria, and not found when the amino acid analyzed was tryptophan, provides evidence of forces restricting the content of cysteine residues in microbial proteins during evolution. We discuss these findings in the context of protein structure and function, antigenicity and immunogenicity, and host-parasite relationships.

scholarly journals Structure and function of factor XI

Blood ◽  
2010 ◽  
Vol 115 (13) ◽  
pp. 2569-2577 ◽  
Author(s):  
Jonas Emsley ◽  
Paul A. McEwan ◽  
David Gailani
Keyword(s):  
Catalytic Domain ◽  
Structural Features ◽  
Factor Ix ◽  
Missense Mutations ◽  
Factor Xi ◽  
Disk Structure ◽  
Ligand Binding Sites ◽  
And Function ◽  
Insight Into

AbstractFactor XI (FXI) is the zymogen of an enzyme (FXIa) that contributes to hemostasis by activating factor IX. Although bleeding associated with FXI deficiency is relatively mild, there has been resurgence of interest in FXI because of studies indicating it makes contributions to thrombosis and other processes associated with dysregulated coagulation. FXI is an unusual dimeric protease, with structural features that distinguish it from vitamin K–dependent coagulation proteases. The recent availability of crystal structures for zymogen FXI and the FXIa catalytic domain have enhanced our understanding of structure-function relationships for this molecule. FXI contains 4 “apple domains” that form a disk structure with extensive interfaces at the base of the catalytic domain. The characterization of the apple disk structure, and its relationship to the catalytic domain, have provided new insight into the mechanism of FXI activation, the interaction of FXIa with the substrate factor IX, and the binding of FXI to platelets. Analyses of missense mutations associated with FXI deficiency have provided additional clues to localization of ligand-binding sites on the protein surface. Together, these data will facilitate efforts to understand the physiology and pathology of this unusual protease, and development of therapeutics to treat thrombotic disorders.

scholarly journals In silico prediction of structure and function for a large family of transmembrane proteins that includes human Tmem41b

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 1395
Author(s):  
Shahram Mesdaghi ◽  
David L. Murphy ◽  
Filomeno Sánchez Rodríguez ◽  
J. Javier Burgos-Mármol ◽  
Daniel J. Rigden
Keyword(s):  
Ab Initio ◽  
Rotational Symmetry ◽  
Domain Boundary ◽  
Pfam Domain ◽  
Transmembrane Proteins ◽  
Large Family ◽  
Data Bank ◽  
Structural Features ◽  
Structure And Function ◽  
And Function

Background: Recent strides in computational structural biology have opened up an opportunity to understand previously uncharacterised proteins.  The under-representation of transmembrane proteins in the Protein Data Bank highlights the need to apply new and advanced bioinformatics methods to shed light on their structure and function.  This study focuses on a family of transmembrane proteins containing the Pfam domain PF09335 ('SNARE_ASSOC'/ ‘VTT ‘/’Tvp38’). One prominent member, Tmem41b, has been shown to be involved in early stages of autophagosome formation and is vital in mouse embryonic development as well as being identified as a viral host factor of SARS-CoV-2. Methods: We used evolutionary covariance-derived information to construct and validate ab initio models, make domain boundary predictions and infer local structural features.  Results: The results from the structural bioinformatics analysis of Tmem41b and its homologues showed that they contain a tandem repeat that is clearly visible in evolutionary covariance data but much less so by sequence analysis.  Furthermore, cross-referencing of other prediction data with covariance analysis showed that the internal repeat features two-fold rotational symmetry.  Ab initio modelling of Tmem41b and homologues reinforces these structural predictions.  Local structural features predicted to be present in Tmem41b were also present in Cl-/H+ antiporters.  Conclusions: The results of this study strongly point to Tmem41b and its homologues being transporters for an as-yet uncharacterised substrate and possibly using H+ antiporter activity as its mechanism for transport.

scholarly journals Structural Features of a Bacteroidetes-Affiliated Cellulase Linked with a Polysaccharide Utilization Locus

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
A.E. Naas ◽  
A.K. MacKenzie ◽  
B. Dalhus ◽  
V.G.H. Eijsink ◽  
P.B. Pope
Keyword(s):  
Active Site ◽  
Three Dimensional ◽  
Structural Features ◽  
Structure And Function ◽  
Dimensional Structure ◽  
Active Site Cleft ◽  
Polysaccharide Utilization Locus ◽  
And Function ◽  
Rumen Metagenome

Abstract Previous gene-centric analysis of a cow rumen metagenome revealed the first potentially cellulolytic polysaccharide utilization locus, of which the main catalytic enzyme (AC2aCel5A) was identified as a glycoside hydrolase (GH) family 5 endo-cellulase. Here we present the 1.8 Å three-dimensional structure of AC2aCel5A and characterization of its enzymatic activities. The enzyme possesses the archetypical (β/α)8-barrel found throughout the GH5 family and contains the two strictly conserved catalytic glutamates located at the C-terminal ends of β-strands 4 and 7. The enzyme is active on insoluble cellulose and acts exclusively on linear β-(1,4)-linked glucans. Co-crystallization of a catalytically inactive mutant with substrate yielded a 2.4 Å structure showing cellotriose bound in the −3 to −1 subsites. Additional electron density was observed between Trp178 and Trp254, two residues that form a hydrophobic “clamp”, potentially interacting with sugars at the +1 and +2 subsites. The enzyme’s active-site cleft was narrower compared to the closest structural relatives, which in contrast to AC2aCel5A, are also active on xylans, mannans and/or xyloglucans. Interestingly, the structure and function of this enzyme seem adapted to less-substituted substrates such as cellulose, presumably due to the insufficient space to accommodate the side-chains of branched glucans in the active-site cleft.

scholarly journals IX. On the structure and development of the liver

1849 ◽  
Vol 139 ◽  
pp. 109-137 ◽  
Keyword(s):  
Royal Society ◽  
A Priori ◽  
Structural Features ◽  
Structure And Function ◽  
Conclusive Evidence ◽  
Interesting Paper ◽  
Biliary Ducts ◽  
And Function ◽  
Do So

In venturing to offer a second communication to the Royal Society respecting the structure of the liver, I feel the rather anxious to do so, that I may have an opportunity of correcting an error and supplying a deficiency which existed in my previous paper. In the following observations I purpose to present some account of the structure of the liver examined in the ascending series of animals, and also to describe the several stages of its evolution in the embryo; in this way I trust I may be able to exhibit the characteristic structural features of the organ as it exists in Man and the higher animals, and also to determine the true place which ought to be assigned to it in a classification of the various glandular organs occurring in the same. I am not aware that any detailed account of the structure of the liver has been recently published, except that by M. Natalis Guillot, which however, so far as I comprehend it, does not seem to be one that can be readily accepted; the idea that the minute biliary ducts and lymphatics originate together in a common net-work, is à priori improbable, and entirely opposed to conclusive evidence (as I think), which will be subsequently adduced. A very interesting paper on the structure and function of the liver has also appeared in the 4th volume of the Guy’s Hospital Reports, from the pen of Dr. Williams; to his labours I shall several times have occasion to refer, but it will be seen that I differ from him in several particulars, especially respecting the importance of the basement or limitary membrane.

scholarly journals Structure and Function of CC-Chemokine Receptor 5 Homologues Derived from Representative Primate Species and Subspecies of the Taxonomic Suborders Prosimii and Anthropoidea

2003 ◽  
Vol 77 (22) ◽  
pp. 12310-12318 ◽  
Author(s):  
Kevin J. Kunstman ◽  
Bridget Puffer ◽  
Bette T. Korber ◽  
Carla Kuiken ◽  
Una R. Smith ◽  
...  
Keyword(s):  
Amino Acid ◽  
Chemokine Receptor ◽  
Transmembrane Domain ◽  
Structure And Function ◽  
Primate Species ◽  
Amino Acid Substitutions ◽  
Immunodeficiency Virus ◽  
And Function ◽  
Cc Chemokine Receptor 5 ◽  
Hiv 1

ABSTRACT A chemokine receptor from the seven-transmembrane-domain G-protein-coupled receptor superfamily is an essential coreceptor for the cellular entry of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) strains. To investigate nonhuman primate CC-chemokine receptor 5 (CCR5) homologue structure and function, we amplified CCR5 DNA sequences from peripheral blood cells obtained from 24 representative species and subspecies of the primate suborders Prosimii (family Lemuridae) and Anthropoidea (families Cebidae, Callitrichidae, Cercopithecidae, Hylobatidae, and Pongidae) by PCR with primers flanking the coding region of the gene. Full-length CCR5 was inserted into pCDNA3.1, and multiple clones were sequenced to permit discrimination of both alleles. Compared to the human CCR5 sequence, the CCR5 sequences of the Lemuridae, Cebidae, and Cercopithecidae shared 87, 91 to 92, and 96 to 99% amino acid sequence homology, respectively. Amino acid substitutions tended to cluster in the amino and carboxy termini, the first transmembrane domain, and the second extracellular loop, with a pattern of species-specific changes that characterized CCR5 homologues from primates within a given family. At variance with humans, all primate species examined from the suborder Anthropoidea had amino acid substitutions at positions 13 (N to D) and 129 (V to I); the former change is critical for CD4-independent binding of SIV to CCR5. Within the Cebidae, Cercopithecidae, and Pongidae (including humans), CCR5 nucleotide similarities were 95.2 to 97.4, 98.0 to 99.5, and 98.3 to 99.3%, respectively. Despite this low genetic diversity, the phylogeny of the selected primate CCR5 homologue sequences agrees with present primate systematics, apart from some intermingling of species of the Cebidae and Cercopithecidae. Constructed HOS.CD4 cell lines expressing the entire CCR5 homologue protein from each of the Anthropoidea species and subspecies were tested for their ability to support HIV-1 and SIV entry and membrane fusion. Other than that of Cercopithecus pygerythrus, all CCR5 homologues tested were able to support both SIV and HIV-1 entry. Our results suggest that the shared structure and function of primate CCR5 homologue proteins would not impede the movement of primate immunodeficiency viruses between species.

scholarly journals The Significance of Calcium in Photosynthesis

2019 ◽  
Vol 20 (6) ◽  
pp. 1353 ◽  
Author(s):  
Quan Wang ◽  
Sha Yang ◽  
Shubo Wan ◽  
Xinguo Li
Keyword(s):  
Signal Transduction ◽  
Binding Sites ◽  
Current Knowledge ◽  
Structure And Function ◽  
Biochemical Reactions ◽  
Chloroplast Proteins ◽  
Secondary Messenger ◽  
And Function ◽  
The Relationship ◽  
Physiological And Biochemical

As a secondary messenger, calcium participates in various physiological and biochemical reactions in plants. Photosynthesis is the most extensive biosynthesis process on Earth. To date, researchers have found that some chloroplast proteins have Ca2+-binding sites, and the structure and function of some of these proteins have been discussed in detail. Although the roles of Ca2+ signal transduction related to photosynthesis have been discussed, the relationship between calcium and photosynthesis is seldom systematically summarized. In this review, we provide an overview of current knowledge of calcium’s role in photosynthesis.

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