Repurposing of Synaptonemal Complex Proteins for Kinetochores in Kinetoplastida

Eelco C. Tromer, Thomas A. Wemyss, Ross F. Waller, Bungo Akiyoshi

Preprint posted on 6 February 2021

Article now published in Open Biology at

Trypanosome kinetochores repurpose components of the synaptonemal complex

Selected by Hiral Shah, Dey Lab


Kinetochores are macromolecular protein complexes that bring about the segregation of chromosomes during cell division. Kinetochores vary across eukaryotes in protein composition and sequence1. A striking example of divergence is seen in Kinetoplastida.  Kinetoplastida are a group of unicellular flagellates including parasites like Trypanosoma and Leishmania spp. within the phylum Euglenozoa. Trypanosoma has a kinetochore made up of KKT/KKIP proteins functionally analogous to the canonical kinetochore found in model organisms, but lacks any direct homologs of its components. Why and how do proteins with such apparently critical cellular functions evolve so rapidly? More specifically, how did this novel/unique kinetoplastid kinetochore emerge? Were they acquired from endosymbionts or did they evolve by repurposing other cellular machinery?

Key findings and future directions

The canonical kinetochore has a mosaic origin, with many components sharing their ancestry with proteins performing a range of functions that include vesicular transport, DNA replication and repair and transcription2. Could this also be true for the kinetoplastids? While it was not possible to identify kinetochore protein homologs, many of the KKT proteins had generic domains shared with proteins involved in homologous recombination, DNA repair and cell cycle regulators like Polo kinases. This provided a clue about what might be going on in Kinetoplastids. Interestingly, KKT17/18, two components of the three member KKT16 subcomplex, that likely emerged through gene duplication, displayed a unique domain topology of Armadillo repeats (ARM) with a Pleckstrin homology (PH) domain followed by coiled coils. This domain arrangement is only found in SYCP2, a protein of the synaptonemal complex that links chromosomes during meiotic homologous recombination suggesting a shared evolutionary history and repurposing of meiotic components for different cellular functions in mitosis.


Figure 1: Evolutionary scenario of SYCP2-3 proteins (Figure 5 from preprint, provided under CC BY 4.0 International License)


Using an iterative alignment method that merged clade-specific alignments into a super alignment, the authors identified SYCP2-3 family proteins that were normally difficult to detect or establish relationships with using only metazoan references across eukaryotes, including Giardia, microsporidia and diverse fungi, suggesting an ancient origin of these kinetoplastid kinetochores. Further, most lineages that lacked any SYCP2-3 also have not revealed any synaptonemal complex structures. Therefore, the presence of SYCP2-3 in a proteome could be a potential indicator of the presence of the synaptonemal complex in the organism.

While this gives us a glimpse into the evolutionary history of this unique kinetochore, its relationship with the other present day eukaryotic and ancient kinetochores is still unclear. Did the early kinetoplastids replace their canonical kinetochores with this new one? Or did early eukaryotes have a kinetochore different from all systems present today, that diverged along these many different paths? Well, only more such studies within the euglenozoa on close relatives like Diplonemida, and across eukaryotes more broadly, will provide a better picture of the ancestry of this unique and essential kinetochore complex. 



  1. van Hooff JJ, Tromer E, van Wijk LM, Snel B, Kops GJ.Evolutionary dynamics of the kinetochore network in eukaryotes as revealed by comparative genomics. EMBO Rep. 2017;18(9):1559-1571. 
  2. Eelco C Tromer, Jolien J E van Hooff, Geert J P L Kops, Berend Snel. Mosaic origin of the eukaryotic kinetochore. Proc Natl Acad Sci U S A. 116(26):12873-12882. doi: 10.1073/pnas.1821945116.





Posted on: 17 May 2021 , updated on: 18 May 2021


Read preprint (No Ratings Yet)

Have your say

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sign up to customise the site to your preferences and to receive alerts

Register here

Also in the cell biology category:

CellBio 2022 – An ASCB/EMBO Meeting

This preLists features preprints that were discussed and presented during the CellBio 2022 meeting in Washington, DC in December 2022.


List by Nadja Hümpfer et al.


The advances in fibroblast biology preList explores the recent discoveries and preprints of the fibroblast world. Get ready to immerse yourself with this list created for fibroblasts aficionados and lovers, and beyond. Here, my goal is to include preprints of fibroblast biology, heterogeneity, fate, extracellular matrix, behavior, topography, single-cell atlases, spatial transcriptomics, and their matrix!


List by Osvaldo Contreras

EMBL Synthetic Morphogenesis: From Gene Circuits to Tissue Architecture (2021)

A list of preprints mentioned at the #EESmorphoG virtual meeting in 2021.


List by Alex Eve

FENS 2020

A collection of preprints presented during the virtual meeting of the Federation of European Neuroscience Societies (FENS) in 2020


List by Ana Dorrego-Rivas

Planar Cell Polarity – PCP

This preList contains preprints about the latest findings on Planar Cell Polarity (PCP) in various model organisms at the molecular, cellular and tissue levels.


List by Ana Dorrego-Rivas

BioMalPar XVI: Biology and Pathology of the Malaria Parasite

[under construction] Preprints presented at the (fully virtual) EMBL BioMalPar XVI, 17-18 May 2020 #emblmalaria


List by Dey Lab, Samantha Seah


Cell Polarity

Recent research from the field of cell polarity is summarized in this list of preprints. It comprises of studies focusing on various forms of cell polarity ranging from epithelial polarity, planar cell polarity to front-to-rear polarity.


List by Yamini Ravichandran

TAGC 2020

Preprints recently presented at the virtual Allied Genetics Conference, April 22-26, 2020. #TAGC20


List by Maiko Kitaoka et al.

3D Gastruloids

A curated list of preprints related to Gastruloids (in vitro models of early development obtained by 3D aggregation of embryonic cells). Updated until July 2021.


List by Paul Gerald L. Sanchez and Stefano Vianello

ECFG15 – Fungal biology

Preprints presented at 15th European Conference on Fungal Genetics 17-20 February 2020 Rome


List by Hiral Shah

ASCB EMBO Annual Meeting 2019

A collection of preprints presented at the 2019 ASCB EMBO Meeting in Washington, DC (December 7-11)


List by Madhuja Samaddar et al.

EMBL Seeing is Believing – Imaging the Molecular Processes of Life

Preprints discussed at the 2019 edition of Seeing is Believing, at EMBL Heidelberg from the 9th-12th October 2019


List by Dey Lab


Preprints on autophagy and lysosomal degradation and its role in neurodegeneration and disease. Includes molecular mechanisms, upstream signalling and regulation as well as studies on pharmaceutical interventions to upregulate the process.


List by Sandra Malmgren Hill

Lung Disease and Regeneration

This preprint list compiles highlights from the field of lung biology.


List by Rob Hynds

Cellular metabolism

A curated list of preprints related to cellular metabolism at Biorxiv by Pablo Ranea Robles from the Prelights community. Special interest on lipid metabolism, peroxisomes and mitochondria.


List by Pablo Ranea Robles

BSCB/BSDB Annual Meeting 2019

Preprints presented at the BSCB/BSDB Annual Meeting 2019


List by Dey Lab


This list of preprints is focused on work expanding our knowledge on mitochondria in any organism, tissue or cell type, from the normal biology to the pathology.


List by Sandra Franco Iborra

Biophysical Society Annual Meeting 2019

Few of the preprints that were discussed in the recent BPS annual meeting at Baltimore, USA


List by Joseph Jose Thottacherry

ASCB/EMBO Annual Meeting 2018

This list relates to preprints that were discussed at the recent ASCB conference.


List by Dey Lab, Amanda Haage

Also in the evolutionary biology category: