# Studies on the mechanisms governing selenium incorporation into proteins - administrative supplement for acquisition of MALS-RI detector

> **NIH NIH R01** · UNIVERSITY OF ILLINOIS AT CHICAGO · 2020 · $137,030

## Abstract

Project Summary. Selenium, an essential micronutrient for human health, exerts its biological role as the amino
acid selenocysteine (Sec). Selenium deficiency, mutations in selenoprotein genes, and low levels of
selenoproteins lead to diseases affecting various organ systems. Also, inefficient Sec incorporation diminishes
selenoenzyme activity and selenoprotein structure. Despite its significance, the mechanism of Sec incorporation
into a nascent selenoprotein is not well understood. This question is at the focus of our original proposal.
However, the absence of a method permitting analysis of the composition and stoichiometry of
ribonucleoprotein complexes that catalyze specific reactions of Sec formation creates barriers to progress and
innovation. We seek funding to obtain multi-angle light scattering and refractive index (MALS-RI) detector
that will enable us to precisely characterize multimolecular assemblies typifying anabolic cycle of Sec.
 According to the current model, the specialized elongation factor, eEFSec, delivers Sec-tRNASec to the
ribosome in response to an in-frame UGA codon. Accurate decoding of the UGA codon also requires auxiliary
protein (SBP2) and RNA (SECIS) factors that are absent from the canonical translational machinery.
Understanding structure, composition, architecture and stoichiometry of macromolecular assemblies governing
Sec incorporation will advance our understanding of selenoprotein synthesis. In the original project, we
proposed to use size-exclusion chromatography coupled to small-angle X-ray scattering (SEC-SAXS) to analyze
both the eEFSec-tRNASec complex (Specific Aim 1) and the ‘recruitment’ complex comprised of SBP2, SECIS,
eEFSec, and Sec-tRNASec (Specific Aim 2). SEC-SAXS is quite powerful but the sample requirements correlate
with the target size and, at some point, this method becomes too prohibitive to use. Also, SEC-SAXS is often not
sensitive enough to detect oligomers, aggregates and complexes of slightly different compositions that may be
present in the sample. Clearly, having access to an approach that would be able to discern among distinct
macromolecular species in the same sample would be instrumental to success of our structural and mechanistic
studies.
 Recently, we probed the utility of the MALS-RI detector for our studies. Because of the instrument
configuration, individual ribonucleoprotein complexes, proteins and nucleic acids were eluted from the SEC
column through the MALS-RI detector and then through the SAXS sample chamber. This particular
configuration enabled concurrent collection and comparison of the MALS-RI and SAXS data. After running a
series of tests, the conclusion is that MALS-RI should be routinely used in our studies, particularly when
multicomponent systems are being studied. However, MALS-RI is not easily accessible within the Chicagoland
area. The only detector is at the BioCAT beamline, but this particular detector can only be used when the beam
station is not used...

## Key facts

- **NIH application ID:** 10135323
- **Project number:** 3R01GM097042-08S1
- **Recipient organization:** UNIVERSITY OF ILLINOIS AT CHICAGO
- **Principal Investigator:** Miljan Simonovic
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $137,030
- **Award type:** 3
- **Project period:** 2012-05-01 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10135323

## Citation

> US National Institutes of Health, RePORTER application 10135323, Studies on the mechanisms governing selenium incorporation into proteins - administrative supplement for acquisition of MALS-RI detector (3R01GM097042-08S1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10135323. Licensed CC0.

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