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Estela Pineda-Molina

Publications and source records attributed to Estela Pineda-Molina.

4 recordsLinked to original sources
PubMed2006

The crystal structure of the C-terminal domain of Vps28 reveals a conserved surface required for Vps20 recruitment.

The endosomal sorting complex I required for transport (ESCRT-I) is composed of the three subunits Vps23/Tsg101, Vps28 and Vps37. ESCRT-I is recruited to cellular membranes during multivesicular endosome biogenesis and by enveloped viruses such as HIV-1 to mediate budding from the cell. Here, we describe the crystal structure of a conserved C-terminal domain from Sacharomyces cerevisiae Vps28 (Vps28-CTD) at 3.05 A resolution which folds independently into a four-helical bundle structure. Co-expression experiments of Vps28-CTD, Vps23 and Vps37 suggest that Vps28-CTD does not directly participate in ESCRT-I assembly and may thus act as an adaptor module for downstream interaction partners. We show through mutagenesis studies that Vps28-CTD employs its strictly conserved surface in the interaction with the ESCRT-III factor Vps20. Furthermore, we present evidence that Vps28-CTD is sufficient to rescue an equine infectious anaemia virus (EIAV) Gag late domain deletion. Vps28-CTD mutations abolishing Vps20 interaction in vitro also prevent the rescue of the EIAV Gag late domain mutant consistent with a potential direct Vps28-ESCRT-III Vps20 recruitment. Therefore, the physiological relevant EIAV Gag-Alix interaction can be functionally replaced by a Gag-Vps28-CTD fusion. Because both Alix and Vps28-CTD can directly recruit ESCRT-III proteins, ESCRT-III assembly coupled to Vps4 action may therefore constitute the minimal budding machinery for EIAV release.

Amino Acid Sequence↗
PubMed2006

Structural basis for budding by the ESCRT-III factor CHMP3.

The vacuolar protein sorting machinery regulates multivesicular body biogenesis and is selectively recruited by enveloped viruses to support budding. Here we report the crystal structure of the human ESCRT-III protein CHMP3 at 2.8 A resolution. The core structure of CHMP3 folds into a flat helical arrangement that assembles into a lattice, mainly via two different dimerization modes, and unilaterally exposes a highly basic surface. The C terminus, the target for Vps4-induced ESCRT disassembly, extends from the opposite side of the membrane targeting region. Mutations within the basic and dimerization regions hinder bilayer interaction in vivo and reverse the dominant-negative effect of a truncated CHMP3 fusion protein on HIV-1 budding. Thus, the final steps in the budding process may include CHMP protein polymerization and lattice formation on membranes by employing different bilayer-recognizing surfaces, a function shared by all CHMP family members.

Amino Acid Sequence↗
PubMed2002

Contribution of covalent protein modification to the antiinflammatory effects of cyclopentenone prostaglandins.

Cyclopentenone prostaglandins, which are produced during inflammatory processes, may exert a negative feedback on inflammation. These reactive compounds may form covalent adducts with thiol groups in glutathione or in proteins. The transcription factor NF-kappaB is key for the expression of numerous proinflammatory genes. We have observed that treatment of mesangial cells with 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) inhibits the cytokine-elicited DNA binding activity of NF-kappaB, both in intact cells and in isolated nuclear extracts, thus suggesting a direct effect on DNA binding. By using a biotinylated 15d-PGJ(2) derivative, we have observed that 15d-PGJ(2) forms an adduct with the p50 subunit of NF-kappaB, as shown by Western blot and detection with horseradish peroxidase-conjugated streptavidin. In contrast, a p50 construct that bears a mutation in the cysteine residue involved in DNA binding (Cys62Ser) and is not susceptible to inhibition by 15d-PGJ(2) does not incorporate biotinylated 15d-PGJ(2). The labeling of several polypeptides after incubation of cells with biotinylated 15d-PGJ(2) suggests that there may be multiple targets for modification by 15d-PGJ(2). We propose that the covalent modification of NF-kappaB (and potentially other proteins) by 15d-PGJ(2) may contribute to the antiinflammatory effects of this prostaglandin.

Animals↗