Arabidopsis Zinc Ribbon 3 is the ortholog of yeast mitochondrial HSP70 escort protein HEP1 and belongs to an ancient protein family in mitochondria and plastids

Abstract

Edited by Ulf-Ingo FluggeKeywords: Mitochondria Protein import Chaperone HSP ETCHED1 ZIM17/TIM15 a b s t r a c t ZR proteins belong to a phylogenetically conserved family of small zinc-ribbon proteins in plastids and mitochondria of higher plants. The function of these proteins is so far unclear. The mitochondrial proteins share sequence similarities with mitochondrial Hsp70 escort proteins (HEP) from Saccharomyces cerevisiae (HEP1) and human. Expression of the mitochondrial ZR protein from Arabidopsis, ZR3, rescued a hep1 knockout mutant from yeast. Accordingly, ZR3 was found to physically interact with mitochondrial Hsp70 from Arabidopsis. Our findings support the idea that mitochondrial and plastidic ZR proteins from higher plants are orthologs of HEP proteins. Structured summary of protein interactions:ZR3 physically interacts with mtHSC70-2 by pull down (View interaction) ZR3 physically interacts with mtHSC70-1 by pull down (View interaction)

Plasmodium falciparum Hep1 Is Required to Prevent the Self Aggregation of PfHsp70-3

“…Based on the observation that mitochondrial members of the plant zinc ribbon (ZR) protein family show sequence similarities to Hep1 from yeast and humans, ZR and Hep proteins were classified as part of a family consisting of five subgroups: ZR1, ZR2, ZR3, Hep1 and Hep2 [ 42 ]. The classification was based on sequence identity and sub-cellular localization of individual proteins within the cell [ 42 ]. The ZR subfamily refers to plant zinc finger proteins, ZR1 and ZR2 being plastidic and ZR3 residing within the mitochondria.…”

“…The ZR subfamily refers to plant zinc finger proteins, ZR1 and ZR2 being plastidic and ZR3 residing within the mitochondria. The Hep subfamily refers to non-plant zinc finger proteins with Hep1 being mitochondrial and Hep2 being plastidic [ 42 ]. The putative mitochondrial targeting sequence and the zinc finger domain (zf-DNL) of the hypothetical zinc finger protein from P .…”

“…Hep and ZR proteins have been observed to play roles in suppressing the self-aggregation of the respective mtHsp70 orthologues in humans [ 23 ], yeast [ 19 , 21 ], Leishmania [ 39 ], green algae [ 43 ] and in Arabidopsis thaliana [ 42 ]. The primary structure of full-length PfHep1 was aligned with its orthologues and the putative mitochondrial or chloroplast signal peptides are highlighted for each sequence ( Fig 1A ).…”

Caracterização estrutural e funcional da construção do domínio >i<core>/i< da Hep1 humana (hHep1_>i<core>/i<)

“…As Hep são cochaperonas conservadas em diversos eucariotos que atuam prevenindo a autoagregação de Hsp70s. São identificadas ortólogas mitocondriais (Hep1) e plastídicas (Hep2), a diferenciação nestas subfamílias é determinada pela sequência de encaminhamento, para mitocôndrias ou cloroplastos, presentes em suas estruturas (KLUTH et al, 2012). A ausência de Heps em procariotos pode indicar que ela tenha evoluido após o processo de endossímbiose de bactérias, originando mitocôndrias (YAMAMOTO et al, 2005).…”

“…Esta função, desenvolvida por Shen e Sali(2006), avalia o potencial estatístico dependente da distância atômica. O gráfico de Ramachandram avalia as posições possíveis dos resíduos em função dos ângulos diedros  e , foi construído utilizando o programa SAVES v6.0(LASKOWSKI et al, 1993).As imagens do modelo de estrutura 3D da hHep1_core, a partir do arquivo de coordenadas gerados pelo software Modeller, foram editadas utilizando o software Chimera(YANG et al, 2012). (b) Espectropolarimetria de dicroísmo circularAs análises de espectropolarimetria de CD foram realizadas a fim de se avaliar a composição de estruturas secundárias da construção truncada.Foram utilizadas amostras de hHep1_core com concentrações entre 15 e 20 M.…”