Abstract:
The primary sequences of biopolymers including RNA and proteins are widely conserved between different species, which are folded into specific three-dimensional structures, resulting in specific molecular interactions that regulate various biological reactions. This has long been a dogma

of molecular biology. However, recent studies have identified a number of novel biopolymers that exert their molecular functions without known conserved functional domains. We designate these molecules as “non-domain biopolymers, which assumingly function without being folded into distinct structures.
Representative examples of known non-domain biopolymers of important molecular functions include the long noncoding RNA NEAT1 that functions as an architectural component of nonmembranous organelle paraspeckles, super-disordered Hero proteins that strongly inhibit the formation of disease-related molecular aggregates. In this seminar, we will introduce phenotypic analyses of mutant mice of these nondomain biopolymers, and discuss how they expert their functions.

References:

1. Nakagawa, S., Yamazaki, T., Mannen, T. and Hirose, T. (2021). ArcRNAs and the formation of nuclear bodies. Mamm Genome. DOI: 10.1007/s00335-021-09881-5
(A review article on the role and function of architectural lncRNAs that function in non-membraneous organelles)

2. West, J. A., Mito, M., Kurosaka, S., Takumi, T., Tanegashima, C., Chujo, T., Yanaka, K., Kingston, R. E., Hirose, T., Bond, C. et al. (2016). Structural, super-resolution microscopy analysis of paraspeckle nuclear body organization. J Cell Biol 214, 817-30. DOI: 10.1083/jcb.201601071
(The first paper describing fine structures of nuclear nonmembranous organelles observed with structured illumination microscope)

3. Tsuboyama, K., Osaki, T., Matsuura-Suzuki, E., Kozuka-Hata, H., Okada, Y., Oyama, M., Ikeuchi, Y., Iwasaki, S. and Tomari, Y. (2020). A widespread family of heat-resistant obscure (Hero) proteins protect against protein instability and aggregation. PLoS Biol 18, e3000632. DOI: 10.1371/journal.pbio.3000632
(A seminal study firstly demonstrated the presence and the molecular functions of super-disordered proteins in mammalian genomes)