Mitochondrial Band-7 family proteins: scaffolds for respiratory chain assembly?

Abstract

The band-7 protein family comprises a diverse set of membrane-bound proteins characterized by the presence of a conserved domain. The exact function of this band-7 domain remains elusive, but examples from animal and bacterial stomatin-type proteins demonstrate binding to lipids and the ability to assemble into membrane-bound oligomers that form putative scaffolds. Some members, such as prohibitins (PHB) and human stomatin-like protein 2 (HsSLP2), localize to the mitochondrial inner membrane where they function in cristae formation and hyperfusion. In Arabidopsis, the band-7 protein family has diversified and includes plant-specific members. Mitochondrial-localized members include prohibitins (AtPHBs) and two stomatin-like proteins (AtSLP1 and -2). Studies into PHB function in plants have demonstrated an involvement in root meristem proliferation and putative scaffold formation for mAAA proteases, but it remains unknown how these roles are achieved at the molecular level. In this minireview we summarize the current status of band-7 protein functions in Arabidopsis, and speculate how the mitochondrial members might recruit specific lipids to form microdomains that could shape the organization and functioning of the respiratory chain.

Life without complex I: proteome analyses of an Arabidopsis mutant lacking the mitochondrial NADH dehydrogenase complex

“…SLPs can bind cardiolipin and interact with prohibitins ( Mitsopoulos et al , 2015 ). Similar interactions have also been reported for the mitochondria of plants ( Gehl et al , 2014 ; Gehl and Sweetlove, 2014 ). Knock-out mutants for slp1 have reduced complex I levels and activity, and form lower amounts of supercomplexes, indicating that SLPs and prohibitins can affect the assembly and/or the stability of OXPHOS complexes ( Gehl et al , 2014 ).…”

Nuclear Prohibitin3 Maintains Genome Integrity and Cell Proliferation in the Root Meristem through Minichromosome Maintenance 2

“…The essential role of PHB3 in root development and the cell cycle prompted us to further explore the potential mechanism of its action. The previous data showed that the functions of prohibitin proteins are conserved (Snedden and Fromm, 1997;Ahn et al, 2006;Van Aken et al, 2007;Gehl and Sweetlove, 2014), and the homo PHB1, which is the closest homology of PHB3 in Arabidopsis, is involved in modulating the cell cycle via physically interacting with MCM complex members MCM2, MCM5, and MCM7 in vitro (Rizwani et al, 2009). Intriguingly, MCM2 has been reported to play an essential role on embryo and root meristem development, because disruption of MCM2 is lethal at the very early embryogenesis stage and its over-expression results in reduced root growth (Ni et al, 2009), implying a possible role of MCM2 in modulating primary root development in the phb3 mutant.…”

Functional Prediction of Hypothetical Proteins from Shigella flexneri and Validation of the Predicted Models by Using ROC Curve Analysis

“…On the other hand, WP_000755956.1 has been predicted to belong to the band-7 protein family that comprises of a diverse set of membrane-bound proteins characterized by the presence of a conserved domain [72]. The exact function of this domain is not known, but concurrent reports from animal and bacterial stomatin-type proteins demonstrate the ability of binding to lipids and in the assembly of membrane-bound oligomers that form putative scaffolds [73]. We have also predicted WP_001269672.1 and WP_000749269.1 as the lipid binding domain called lipopolysaccharide (LPS)-assembly lipoprotein LptE and the YceI-like domain respectively.…”