FEZ2 Has Acquired Additional Protein Interaction Partners Relative to FEZ1: Functional and Evolutionary Implications

Abstract

BackgroundThe FEZ (fasciculation and elongation protein zeta) family designation was purposed by Bloom and Horvitz by genetic analysis of C. elegans unc-76. Similar human sequences were identified in the expressed sequence tag database as FEZ1 and FEZ2. The unc-76 function is necessary for normal axon fasciculation and is required for axon-axon interactions. Indeed, the loss of UNC-76 function results in defects in axonal transport. The human FEZ1 protein has been shown to rescue defects caused by unc-76 mutations in nematodes, indicating that both UNC-76 and FEZ1 are evolutionarily conserved in their function. Until today, little is known about FEZ2 protein function.Methodology/Principal FindingsUsing the yeast two-hybrid system we demonstrate here conserved evolutionary features among orthologs and non-conserved features between paralogs of the FEZ family of proteins, by comparing the interactome profiles of the C-terminals of human FEZ1, FEZ2 and UNC-76 from C. elegans. Furthermore, we correlate our data with an analysis of the molecular evolution of the FEZ protein family in the animal kingdom.Conclusions/SignificanceWe found that FEZ2 interacted with 59 proteins and that of these only 40 interacted with FEZ1. Of the 40 FEZ1 interacting proteins, 36 (90%), also interacted with UNC-76 and none of the 19 FEZ2 specific proteins interacted with FEZ1 or UNC-76. This together with the duplication of unc-76 gene in the ancestral line of chordates suggests that FEZ2 is in the process of acquiring new additional functions. The results provide also an explanation for the dramatic difference between C. elegans and D. melanogaster unc-76 mutants on one hand, which cause serious defects in the nervous system, and the mouse FEZ1 -/- knockout mice on the other, which show no morphological and no strong behavioural phenotype. Likely, the ubiquitously expressed FEZ2 can completely compensate the lack of neuronal FEZ1, since it can interact with all FEZ1 interacting proteins and additional 19 proteins.

RAB3GAP1 and RAB3GAP2 modulate basal and rapamycin-induced autophagy

“…However, both FEZ proteins have overlapping functions 49 and we show that they have identical effects on autophagy in the cell system employed here. Thus, we propose that a direct interaction of FEZ1 and the RAB3-GAPs, which we could not transfer into mammalian cells employing co-immunoprecipitation and IP/MS approaches, is actually not a strict prerequisite for the opposing activities of RAB3GAP1/2 and FEZ1/2 on autophagy.…”

“…Notably, in yeast 2-hybrid studies analyzing FEZ1 38 and FEZ2 49 the RAB3GAPs have been assigned as interaction partners for FEZ1 but not for FEZ2. However, both FEZ proteins have overlapping functions 49 and we show that they have identical effects on autophagy in the cell system employed here.…”

The molecular motor Myosin Va interacts with the cilia-centrosomal protein RPGRIP1L

“…Yeast cells were transformed with pBTM116_MyoVa-GTD vector and the library as described by Alborghetti and co-workers47. The screen was performed in solid Synthetic Defined Medium without tryptophan, leucine and histidine (SD-WLH) containing 5 mM 3-amino-1,2,4-triazole (3-AT) (Sigma-Aldrich, St. Louis, MO).…”

Structural Analysis of Intermolecular Interactions in the Kinesin Adaptor Complex Fasciculation and Elongation Protein Zeta 1/ Short Coiled-Coil Protein (FEZ1/SCOCO)

“…So, a general picture is emerging that kinesin family members link to their cargoes via adaptor/scaffolding proteins [12], such as UNC-76/-69. Recent studies with the human proteins FEZ1 (=UNC-76) and SCOCO (=UNC-69) further support this notion, since FEZ1 was described as a hub protein, which interacts through its C-terminal coiled-coil region with over 80 different proteins, of different functional classes, that may represent cargoes [11,13,14]. Furthermore, FEZ1 knockdown causes mitochondria mislocalization [15] and vesicle accumulation in the soma of PC12 cells [16], which could be explained by a failure in the transport of these organelles.…”