Small open reading frame-encoded peptides (SEPs) are
microproteins
with a length of 100 amino acids or less, which may play a critical
role in maintaining cell homeostasis under stress. Therefore, we used
mass spectrometry-based proteomics to explore microproteins potentially
involved in cellular stress responses in Saccharomyces
cerevisiae. A total of 225 microproteins with 1920
unique peptides were identified under six culture conditions: normal,
oxidation, starvation, ultraviolet radiation, heat shock, and heat
shock with starvation. Among these microproteins, we found 70 SEPs
with 75 unique peptides. The annotated microproteins are involved
in stress-related processes, such as cell redox reactions, cell wall
modification, protein folding and degradation, and DNA damage repair.
It suggests that SEPs may also play similar functions under stress
conditions. For example, SEP IP_008057, translated from a short coding
sequence of YJL159W, may play a role in heat shock.
This study identified stress-responsive SEPs in S.
cerevisiae and provided valuable information to determine
the functions of these proteins, which enrich the genome and proteome
of S. cerevisiae and show clues to
improving the stress tolerance of S. cerevisiae.