A novel ribosomes (RibosomeST) in spermatogenesis are capable of producing sperm-specific proteomes

Ribosomes are one of the most important polymerases, using messenger RNA (mRNA) as a template and aminoacylated tRNA (aa-tRNA) as a substrate, a factory for protein synthesis
.
Ribosomes have millions to tens of millions of copies in each mammalian cell [1,2].

Ribosomes themselves also account for a large proportion of the cell's material, ribosomal RNA (rRNA) accounts for 80-85% of the total RNA in all cell types, ribosomal protein (rProtein) accounts for 5-10% of the total protein amount in mammals, 10-20% of the total protein copy number [1] (Figure 1).

Figure 1.
Ribosome structure diagram and ribosome participation in protein synthesis working principle diagram

(A) Ribosomes are factories
for protein synthesis using messenger RNA (mRNA) as a template and aminoacylated transport RNA (aa-tRNA) as a substrate.
(B) tRNA moves in the ribosome, which is the logistics on the production line in the protein synthesis factory [3,4] (C) The basic structure of the ribosome and the proportion of intracellular copy number and occupied substances [1].

On December 14, 2022, the team of Sha Jiahao and Guo Xuejiang of Nanjing Medical University and the team of Qin Yan of the Institute of Biophysics of the Chinese Academy of Sciences published the article "A male germ-cell-specific ribosome controls male fertility" in Nature, and found that the novel ribosome^ST in spermatogenesis can produce sperm-specific
。

Ribosomes are direct 20~30nm near-spheroids, and a wide range of ribosomes can be seen in high-resolution imaging of cells (Figure 2).

In rapidly proliferating cells, ribosomes occupy a higher proportion of material and energy, and histiocytes develop and determine cell fate (Qin Yan's research group in Science Bulletin review in July 2022 [5]).

Special ribosomes can produce special proteomes, thereby determining the function and fate of cells, which is an important proposition in recent years, and the production of proteins, the main carrier for understanding cell function, is a fundamental problem: how ribosomes determine proteomes
.

Figure 2.
(A) Ribosomes
in situ state of different cells presented by cryo-electron microscopy.
(B) Focused ion beam microscopy combined with artificial intelligence technology to remodel cellular components
.
【3】

In male germ cells, the ribosomal large subunit protein L39, which metastasizes after meiosis of spermatogenesis and uses the form of L39L on
the ribosome.
The study found that L39 is an important component on the ribosomal large subunit neopeptide chain channel, and after L39L replaces L39, this channel can be much wider, which is conducive to the production
of a large number of positive electroproteins in sperm maturation.
So how does ribosomal L39 determine the sperm reproductive proteome?

Through the super-resolved cryo-EM structure elucidation of L39L ribosomes (Ribosome ST) and ordinary L39 ribosomes (Ribosome⁾ (resolution of 2.
82 angstroms in L39 and 3.
03 angstroms in L39L), the researchers found important components on the ribosomal large subunit neonatal peptide chain channel, which can be much wider after L39L replaces L39, which is conducive to
。

Fig.
3 The special ribosome^ST in spermatogenesis replaces ordinary L39 (right, purple protein) with L39L (right, red protein), resulting in a widening of ribosomal neopeptide chain channels, which contributes to the production
of a large number of positively charged neopeptide chains in spermatogenesis.

Spermatogenesis is the core function of species reproduction, and oligospermia is an important national health problem in recent years, and this research will provide important markers and therapeutic targets
for related diseases.

Article link: style="text-align:justify;" _msthash="101749" _msttexthash="168129">References:

　　1.
An, H.
, and Harper, J.
W.
(2020) Ribosome Abundance Control Via the Ubiquitin-Proteasome System and Autophagy.
J Mol Biol 432, 170-184

　　2.
An, H.
, Ordureau, A.
, Korner, M.
, Paulo, J.
A.
, and Harper, J.
W.
(2020) Systematic quantitative analysis of ribosome inventory during nutrient stress.
Nature 583, 303-309

　　3.
Wang, Q.
, Wang, Y.
B.
, Li, S.
G.
, Zhou, A.
Q.
, and Qin, Y.
(2022) Organelle biogenesis: ribosomes as organizer and performer.
Science Bulletin 67, 1614-1617

　　4.
Liu, G.
, Song, G.
, Zhang, D.
, Zhang, D.
, Li, Z.
, Lyu, Z.
, Dong, J.
, Achenbach, J.
, Gong, W.
, Zhao, X.
S.
, Nierhaus, K.
H.
, and Qin, Y.
(2014) EF-G catalyzes tRNA translocation by disrupting interactions between decoding center and codon-anticodon duplex.
Nat Struct Mol Biol 21, 817-824

　　5.
Zhang, D.
, Yan, K.
, Liu, G.
, Song, G.
, Luo, J.
, Shi, Y.
, Cheng, E.
, Wu, S.
, Jiang, T.
, Lou, J.
, Gao, N.
, and Qin, Y.
(2016) EF4 disengages the peptidyl-tRNA CCA end and facilitates back-translocation on the 70S ribosome.
Nat Struct Mol Biol 23, 125-131

(Contributed by: Qin Yan Research Group)