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Comparative Analysis of Aggregation of Thermus thermophilus Ribosomal Protein bS1 and Its Stable Fragment

S. Yu. Grishin1, U. F. Dzhus1, O. M. Selivanova1, V. A. Balobanov1, A. K. Surin1,2,3,a, and O. V. Galzitskaya1,4,b*

1Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia

2State Research Center for Applied Microbiology and Biotechnology, 142279 Obolensk, Moscow Region, Russia

3Branch of the Institute of Bioorganic Chemistry, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia

4Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia

* To whom correspondence should be addressed.

Received October 21, 2019; Revised December 24, 2019; Accepted January 11, 2020
Functionally important multidomain bacterial protein bS1 is the largest ribosomal protein of subunit 30S. It interacts with both mRNA and proteins and is prone to aggregation, although this process has not been studied in detail. Here, we obtained bacterial strains overproducing ribosomal bS1 protein from Thermus thermophilus and its stable fragment bS1(49) and purified these proteins. Using fluorescence spectroscopy, dynamic light scattering, and high-performance liquid chromatography combined with mass spectrometric analysis of products of protein limited proteolysis, we demonstrated that disordered regions at the N- and C-termini of bS1 can play a key role in the aggregation of this protein. The truncated fragment bS1(49) was less prone to aggregation compared to the full-size bS1. The revealed properties of the studied proteins can be used to obtain protein crystals for elucidating the structure of the bS1 stable fragment.
KEY WORDS: protein aggregation, ribosomal protein, bS1, domain, Thermus thermophilus, solution ionic strength, mass spectrometry

DOI: 10.1134/S0006297920030104