New insights into the structure and evolution of NMCP proteins, plant analogs of lamins

A new publication performed in the Centro de Investigaciones Biológicas by Dr Susana Moreno  and Dr Malgorzata Ciska provides new insight about the origin, evolution and structure of the plant specific Nuclear Matrix Constituent Protein (NMCP) family, the plant analogues of lamins.

Metazoan lamins are structural components of the lamina and directly promote the association of numerous proteins to the inner nuclear membrane, nuclear pore complexes and chromatin. Plants lack genes encoding lamins but express plant-specific NMCP proteins, which lack the sequence conservation with lamins but share structural and functional similarities. Similar to lamins, NMCPs play key roles in chromatin organization and functional regulation. Hence, they act as lamin functional homologs in plants. The group of Dr Susana Moreno pioneered and led the field of plant nucleoskeleton proteins, being first to propose NMCP proteins as structural and functional homologs of lamins.

This study extends the origin of NMCPs to at least Charophyte algae, the basal Streptophyte that form a separate and distant clade of NMCPs, and establishes that the appearance of additional NMCP homologs in the Streptophyta species was due to whole genome duplication events. The analysis also defines for the first time the structural arrangement of basal NMCPs, uncovers new NMCP-specific domains and describes their conservation in a broad arch of phylogenetic groups. In addition, in situ data uncover that a basal NMCP is a component of the nuclear lamina, supporting, together with the conservation of predicted secondary structures, the functional conservation of these proteins along evolution.

This study is relevant for scientists working in the evolution of nuclear proteins in plants but also to plant cell biologists involved in nuclear envelope and lamina protein fields, as well as those studying chromatin organization and the cellular processes regulated by NMCPs. As these proteins play important functions in regulating chromatin structure, epigenetic traits and gene expression, the insight provided by this study may have important implications for understanding fundamental biological processes in plants such as differentiation, germination, immunity, biotic and abiotic stress.

The work was done in collaboration with Dr Kiyoshi Masuda, Hokkaido University, Sapporo, Japan.

Reference: Malgorzata Ciska; Riku Hikida; Kiyoshi Masuda; Susana Moreno Díaz de la Espina, Journal of Experimental Botany, Volume 70, Issue 10, 1 May 2019, Pages 2651–2664, https://doi.org/10.1093/jxb/erz102