Maria Macias - Academia.edu (original) (raw)

Papers by Maria Macias

Communications Chemistry

RAS oncoproteins are molecular switches associated with critical signaling pathways that regulate... more RAS oncoproteins are molecular switches associated with critical signaling pathways that regulate cell proliferation and differentiation. Mutations in the RAS family, mainly in the KRAS isoform, are responsible for some of the deadliest cancers, which has made this protein a major target in biomedical research. Here we demonstrate that a designed bis-histidine peptide derived from the αH helix of the cofactor SOS1 binds to KRAS with high affinity upon coordination to Pd(II). NMR spectroscopy and MD studies demonstrate that Pd(II) has a nucleating effect that facilitates the access to the bioactive α-helical conformation. The binding can be suppressed by an external metal chelator and recovered again by the addition of more Pd(II), making this system the first switchable KRAS binder, and demonstrates that folding-upon-binding mechanisms can operate in metal-nucleated peptides. In vitro experiments show that the metallopeptide can efficiently internalize into living cells and inhibit ...

Nucleosomes are barriers for the binding of most transcription factors, but pioneer factors (PFs)... more Nucleosomes are barriers for the binding of most transcription factors, but pioneer factors (PFs) do bind and facilitate subsequent interactions of other proteins during transcription activation. FoxH1 is a maternal PF essential during embryonic development that interacts with specific GK-forkhead targets. How FoxH1 binds DNA targets has remained elusive for decades until now. We have determined high-resolution structures of human, frog and fish proteins bound to four DNAs. We found that the FoxH1 DNA-binding domain is almost twice the size of other FOX proteins, allowing for a highly specific binding to both minor and major grooves. Consistent with its PF activity, we also quantified that the affinity for DNA is even higher for native mononucleosomes than for linear DNA. Our structures illustrate how binding to distinct GK sites allows FoxH1 to avoid cross-regulation by other FOX proteins that also operate during the maternal-zygotic transition and select canonical TT-forkhead sites.

Smad transcription factors, the main effectors of the TGFβ (transforming growth factor β) network... more Smad transcription factors, the main effectors of the TGFβ (transforming growth factor β) network, have been shaped along the evolution of multicellular animals to regulate essential processes. Smad proteins have a mixed architecture of globular domains and flexible linkers and adopt distinct quaternary structures depending on their activation state and cellular context. Here we studied the structures of full-length Smad4 and Smad2 proteins through an integrative approach combining small-angle X-ray scattering and detailed atomic information obtained from Nuclear Magnetic Resonance spectroscopy, X-ray and molecular dynamic simulations. Both Smad4 and Smad2 populate ensembles of expanded/compact conformations, with the MH1 and MH2 domains tethered by intrinsically disordered linkers that provide conformational freedom to the proteins. In solution, Smad4 is monomeric, whereas Smad2 coexists as monomer-dimer-trimer association states, even without activation. Smad2 dimers, which were p...

Nature Communications, 2021

Ulcerative colitis and Crohn’s disease are forms of inflammatory bowel disease whose incidence an... more Ulcerative colitis and Crohn’s disease are forms of inflammatory bowel disease whose incidence and prevalence are increasing worldwide. These diseases lead to chronic inflammation of the gastrointestinal tract as a result of an abnormal response of the immune system. Recent studies positioned Cortistatin, which shows low stability in plasma, as a candidate for IBD treatment. Here, using NMR structural information, we design five Cortistatin analogues adopting selected native Cortistatin conformations in solution. One of them, A5, preserves the anti-inflammatory and immunomodulatory activities of Cortistatin in vitro and in mouse models of the disease. Additionally, A5 displays an increased half-life in serum and a unique receptor binding profile, thereby overcoming the limitations of the native Cortistatin as a therapeutic agent. This study provides an efficient approach to the rational design of Cortistatin analogues and opens up new possibilities for the treatment of patients that...

Journal of Molecular Biology, 2021

The identification of new drugs for novel therapeutic targets requires the screening of libraries... more The identification of new drugs for novel therapeutic targets requires the screening of libraries containing tens of thousands of compounds. While experimental screenings are assisted by high-throughput technologies, in target-based biophysical assays, such as differential scanning fluorimetry (DFS), the analysis steps must be calculated manually, often combining several software packages. To simplify the determination of the melting temperature (T m) of the target and the change induced by ligand binding (ΔT m), we developed the HTSDSF explorer, a versatile, all-in-one, user-friendly application suite. Implemented as a server-client application, in the primary screenings, HTSDSF explorer pre-analyzes and displays the T m and ΔT m results interactively, thereby allowing the user to study hundreds of conditions and select the primary hits in minutes. This application also allows the determination of preliminary binding constants (K D) through a series of subsequent dose-response assays on the primary hits, thereby facilitating the ranking of validated hits and the advance of drug discovery efforts.

ABSTRACTThioredoxins (Trxs) are ubiquitous enzymes that regulate the redox state in cells. In Dro... more ABSTRACTThioredoxins (Trxs) are ubiquitous enzymes that regulate the redox state in cells. In Drosophila, there are two germline-specific Trxs, Deadhead (Dhd) and TrxT. Both proteins belong to the L(3)mbt malignant brain tumor signature and to the MMS survival network of genes that mediate the cellular response to DNA damage. Dhd is a maternal protein required for early embryogenesis that promotes protamine-histone exchange in fertilized eggs and midblastula transition. TrxT is testis-specific and associates with the lampbrush loops of the Y chromosome.Here we present the first structures of Dhd and TrxT that unveil new features of these Thioredoxins. Dhd is highly positively charged, unusual in canonical Trxs. This positively charged surface can facilitate its approximation to DNA and to protamine oligomers, to promote chromatin remodeling. On the other hand, TrxT contains a C-terminal extension, mostly unstructured and highly flexible, which wraps the conserved core through a clos...

Ulcerative colitis and Crohn's disease are inflammatory bowel diseases (IBD) that lead to chronic... more Ulcerative colitis and Crohn's disease are inflammatory bowel diseases (IBD) that lead to chronic inflammations of the gastrointestinal tract due to an abnormal response of the immune system. Finding new effective drugs to tackle IBD represents a major therapeutic concern since IBD incidence and prevalence is increasing worldwide. Recent studies positioned Cortistatin (CST) as a candidate for IBD treatment due to its anti-inflammatory and immunomodulatory activity. Here, we studied the structural properties of CST using NMR and synthesized and characterized new analogs displaying enriched populations of some native conformations. One of them, Analog 5, preserved the activity against IBD with an increased half-life in serum, overcoming the native hormone limitation and opening the door for the use of CST analogs as therapeutic agents. This work represents a new approach to the rational design of molecules to treat IBD and a possibility for patients that fail to respond to other therapies.

ACS Omega, 2020

A method for conjugating cholesterol to peptide ligands through non-disperse polyethylene glycol ... more A method for conjugating cholesterol to peptide ligands through non-disperse polyethylene glycol (ND-PEG) through a non-hydrolysable linkage is described. The iterative addition of tetraethylene glycol macrocyclic sulfate to cholesterol (Chol) renders a family of highly pure well-defined Chol-PEG compounds with different PEG lengths from 4 up to 20 ethylene oxide units, stably linked through an ether bond. The conjugation of these Chol-PEG compounds to the cyclic (RGDfK) peptide though Lys5 side chains generates different lengths of Chol-PEG-RGD conjugates that retain the oligomer purity of the precursors, as analysis by HRMS and NMR has shown. Other derivatives were synthesized with similar results, such as Chol-PEG-OCH 3 and Chol-PEG conjugated to glutathione and Tf1 peptides through maleimide−thiol chemoselective ligation. This method allows the systematic synthesis of highly pure uniform stable Chol-PEGs, circumventing the use of activation groups on each elongation step and thus reducing the number of synthesis steps.

Genes & Development, 2019

TGF-β receptors phosphorylate SMAD2 and SMAD3 transcription factors, which then form heterotrimer... more TGF-β receptors phosphorylate SMAD2 and SMAD3 transcription factors, which then form heterotrimeric complexes with SMAD4 and cooperate with context-specific transcription factors to activate target genes. Here we provide biochemical and structural evidence showing that binding of SMAD2 to DNA depends on the conformation of the E3 insert, a structural element unique to SMAD2 and previously thought to render SMAD2 unable to bind DNA. Based on this finding, we further delineate TGF-β signal transduction by defining distinct roles for SMAD2 and SMAD3 with the forkhead pioneer factor FOXH1 as a partner in the regulation of differentiation genes in mouse mesendoderm precursors. FOXH1 is prebound to target sites in these loci and recruits SMAD3 independently of TGF-β signals, whereas SMAD2 remains predominantly cytoplasmic in the basal state and set to bind SMAD4 and join SMAD3:FOXH1 at target promoters in response to Nodal TGF-β signals. The results support a model in which signal-indepen...

Trends in Biochemical Sciences, 2015

Smad transcription factors are central to the signal transduction pathway that mediates the numer... more Smad transcription factors are central to the signal transduction pathway that mediates the numerous effects of the TGF-β superfamily of cytokines in metazoan embryo development and adult tissue regeneration and homeostasis. Although Smad proteins are conserved, recent genomesequencing projects have revealed their sequence variation in metazoan evolution, human polymorphism, and cancer. Structural studies of Smads bound to partner proteins and target DNA provided a framework to understand the significance of these evolutionary and pathologic sequence variations. Here we synthesize the extant mutational and structural data to suggest how genetic variation in Smads may affect the structure, regulation, and function of these proteins. Furthermore, we present a web-app that compares Smad sequences and displays Smad protein structures and their disease-associated variants.

Journal of Biomolecular Nmr, 1999

A new pulse sequence is described for the sequential assignment of proline residues in 13 C/ 15 N... more A new pulse sequence is described for the sequential assignment of proline residues in 13 C/ 15 N-labeled proteins by correlating C δ and C α chemical shifts of proline residues with the H α chemical shift of the preceding residue. Notably, the experiment can provide the sequential connectivities in poly-proline stretches, which cannot be determined using standard triple resonance experiments. Excellent solvent suppression is achieved by coherence selection via a heteronuclear gradient echo. The new pulse sequence has been successfully applied to the 11 kDa HRDC domain.

Proteins: Structure, Function, and Bioinformatics, 2008

FF domains are present in three protein families: the splicing factors formin binding protein 11 ... more FF domains are present in three protein families: the splicing factors formin binding protein 11 (FBP11), Prp40, and URN1, the transcription factor CA150, and the p190RhoGTPaserelated proteins. This simplicity in distribution, however, is

Phytochemistry, 1994

The growth-regulatory activity of 13 tetracyclic diterpenoids with kaurane, beyerane and atisane ... more The growth-regulatory activity of 13 tetracyclic diterpenoids with kaurane, beyerane and atisane skeletons isolated from Elaeoselinum species (Umbelliferae) has been tested in six bioassays and their activities were compared with that shown by gibherellic acid, GA,. Seven of the tested substances showed an activity similar or greater than that displayed by GA, at concentrations 1 to 10 pg ml-'. The most active compounds are ent-1 Sa-angeloyloxykaur-16ene-3/?-yl acetate, methyl ent-1%angeloyloxykaur-16ene-19-oate, methyl ent-be.yer-lS-ene-19-oate, methyl ent-14/Itygloyloxybeyer-lS-ene-19-oate (methyl elasclepiate) and ent-beyer-l5-ene-l4/I,19-diol.

Journal of Natural Products, 1991

As a continuation of our phytochemi-cal studies on plants endemic to Com-unidad Valenciana (East ... more As a continuation of our phytochemi-cal studies on plants endemic to Com-unidad Valenciana (East Spain), we have examined the chemical constituents of the aerial parts of Disticboselinum tenuifolium (Lag.) Garcia Martin &amp;amp; Sil-vestre (Umbelliferae), also known as Thapsia ...