Cell complexity: an enzymes multiple functions (Introduction)

by David Turell , Saturday, May 19, 2018, 02:17 (2382 days ago) @ David Turell

Another complex enzyme has had its functions discovered:

https://www.sciencedaily.com/releases/2018/05/180517163337.htm

"A team of Texas A&M and Texas A&M AgriLife Research scientists now have a deeper understanding of a large switch/sucrose non-fermentable (SWI/SNF) protein complex that plays a pivotal role in plant and human gene expression that causes life-threatening diseases such as cancer.

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"The team has been working for years on how microRNAs are produced in the model plant Arabidopsis. MicroRNAs are tiny regulatory RNA molecules widely present in multicellular organisms. In humans, microRNAs inhibit more than 60 percent of human genes and are actively exploited as potent drugs to cure human diseases, according to the scientists.

"In plants, the molecules can also control many aspects of life such as plant architecture, and responses to hostile environmental conditions. MicroRNAs are also widely engineered in agricultural crops and animals for better yield and quality.

"MicroRNAs are produced in a factory inside cells from long substrates that can be hundreds or thousands of bases and also contain a distinct hairpin-structure. The factory contains a scissor-like enzyme called Dicer, and some assistants that help to fetch the long substrates. One of the assistants is known as Serrate protein, Zhang said.

"'Also, the shape of the substrates is very critical for microRNA production," Zhang said. "If the shapes are changed, then the substrates do not fit the Dicer scissor and can not be cut, and microRNAs are not made."

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"'Also, the shape of the substrates is very critical for microRNA production," Zhang said. "If the shapes are changed, then the substrates do not fit the Dicer scissor and can not be cut, and microRNAs are not made."

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"Wang said CHR2 is essential for producing RNA from DNA templates because its ATPase activity breaks down ATP to generate energy.

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"'That meant, CHR2, when brought into the factory by Serrate, changes the settings inside the factory through its motor activity."

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"'The results are significant because they provide an additional unknown layer of microRNA level regulation. For the first time an explanation is provided for many earlier reports showing that the level of microRNA substrates in many cases does not reflect the amount of mature microRNA," according to one reviewer for the paper.

"'The study is novel and exciting. It shows that the secondary structure of microRNA substrates contains a new informational code that needs to be interpreted by CHR2 and Serrate proteins (before operation of the factory)," according to the other reviewers for the paper. (my bold)

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"The groundbreaking work from Zhang's lab reveals the two separate functions for CHR2 in production of microRNAs.

"'The work identifies a unique gene-editing target to control microRNA amount for systematically improving agricultural traits such as plant architecture, yield, quality and response to hostile environments," Zhang said."

Comment: Note my bold. Life runs on information. Enzymes and other proteins carry information to the cells to instruct changes in production. The degree of complexity cannot be developed by chance mutation.