Elongation factor G (EF-G) is a GTPase that is involved in the translocation of bacterial ribosomes along messenger RNA during protein biosynthesis. In contrast to current models, EF-G-dependent GTP hydrolysis is shown to precede, and greatly accelerate, the rearrangement of the ribosome that leads to translocation.

What causes hydrolysis of GTP?

The hydrolysis of the third (γ) phosphate of GTP to create guanosine diphosphate (GDP) and P_i, inorganic phosphate, occurs by the S_N2 mechanism (see nucleophilic substitution) via a pentavalent transition state and is dependent on the presence of a magnesium ion Mg²⁺. ... To become activated, GTPases must bind to GTP.

What hydrolyzes GTP?

Protein synthesis on the ribosome involves a number of different subprocesses, namely initiation of translation, protein elongation, termination and ribosome recycling^1,2. All of these are dependent on guanosine triphosphate (GTP) hydrolysis by auxiliary protein factors known as translational GTPases.

Does EF G hydrolyze GTP?

Translocation is promoted by elongation factor G (EF-G), a large, five-domain GTPase that hydrolyzes GTP during the reaction.

How is GTP used during elongation?

During elongation, GTP facilitates the binding of a new aminoacyl tRNA to the A site of a ribosome. GTP is also an important factor in signal transduction pathways. Here, GTP can be associated with G-protein complexes and is used to regulate the activity of the protein.

209 Elongation: Elongation Factors and GTP

28 related questions found

How is GTP used during elongation quizlet?

How is GTP used during elongation? It aids in the binding of the incoming tRNA to the A site of the ribosome AND It aids in translocating the ribosome one codon down the mRNA.

Does elongation require GTP?

Efficient translocation of mRNA-tRNAs, a process required to move a new codon into the A site, requires the binding of elongation factor G (EF-G) to the ribosome and subsequent guanosine triphosphate (GTP) hydrolysis (6, 7).

In which process protein elongation factor and GTP serves as a energy source?

GTP is used as the energy source during elongation stage of translation.

What is EF-G GTP?

Elongation factor G (EF-G) uses energy stored in GTP to catalyze movement of transfer RNAs and messenger RNA in the ribosome during the translocation step of prokaryotic protein synthesis.

Does translocation use GTP?

The translocation of tRNA and mRNA through the ribosome requires energy, and this is supplied by the hydrolysis of GTP to GDP. Most textbooks show GTP being carried into the ribosome attached to EF-G.

What happens when GTP is hydrolyzed?

The GTP-bound conformation is biologically active and promotes a cellular function, such as signal transduction, cytoskeleton organization, protein synthesis/translocation, or a membrane budding/fusion event. GTP hydrolysis turns off the GTPase switch by converting it to the inactive GDP-bound conformation.

Is GDP phosphorylated to GTP?

GDP consists of a pyrophosphate group, a pentose sugar ribose, and the nucleobase guanine. GDP is the product of GTP dephosphorylation by GTPases, e.g., the G-proteins that are involved in signal transduction. GDP is converted into GTP with the help of pyruvate kinase and phosphoenolpyruvate.

What happens when GTP Cannot be hydrolyzed?

G proteins without hydrolytic activity cannot hydrolyze bound GTP. GAPs cannot activate a nonfunctional enzyme, and the G protein is constitutively active, resulting in unregulated cell division and the formation of tumors.

What is GTP hydrolysis induce MTS?

Role of GTP

The reaction sequence indicates that GTP facilitates binding of protein factors either to tRNA or to the ribosome. Furthermore, hydrolysis of GTP to GDP always precedes dissociation of the bound factor. ... The function of GTP is to induce a conformational change in a macromolecule by binding to it.

How much energy does GTP hydrolysis release?

Figure 1. ATP and GTP hydrolysis release the same quantity of energy. ATPases and GTPases hydrolyse their NTP substrates to NDP and inorganic phosphate; both hydrolysis reactions liberate 53 kJ/mol Gibbs free energy.

What is responsible for GTP binding?

Small GTPases, also known as small G-proteins, bind GTP and GDP likewise, and are involved in signal transduction. These proteins are homologous to the alpha (α) subunit found in heterotrimers, but exist as monomers. They are small (20-kDa to 25-kDa) proteins that bind to guanosine triphosphate (GTP).

What is Translocase in translation?

Translocase is a general term for a protein that assists in moving another molecule, usually across a cell membrane. ... It is also a historical term for the protein now called elongation factor G, due to its function in moving the transfer RNA (tRNA) and messenger RNA (mRNA) through the ribosome.

What is the primary function of EF-G and EF tu?

An excellent example is the mechanism of the elongation cycle in protein synthesis, that uses the elongation factor Tu (EF-Tu) to deliver aminoacyl-tRNA (aa-tRNA) to the mRNA-programmed ribosome, and the elongation factor G (EF-G) to help the translocation of the tRNA–mRNA complex on the ribosome.

What is the function of elongation factor Ts in elongation?

EF-Tu (elongation factor thermo unstable) is a prokaryotic elongation factor responsible for catalyzing the binding of an aminoacyl-tRNA (aa-tRNA) to the ribosome. It is a G-protein, and facilitates the selection and binding of an aa-tRNA to the A-site of the ribosome.

How many elongation factors are involved in elongation of polypeptide chain in bacteria?

The elongation phase of translation leads to the decoding of the mRNA and the synthesis of the corresponding polypeptide chain. In most eukaryotes, two distinct protein elongation factors (eEF-1 and eEF-2) are required for elongation. Each is active as a complex with GTP.

What does an elongation factor do?

Abstract. Translation elongation factors perform critical functions in protein synthesis in all domains of life, including the delivery of aminoacyl-tRNAs into the ribosome, and the translocation of peptidyl-tRNA from the ribosomal A-site to the ribosomal P-site.

What is the role of elongation factors in translation?

Elongation factors are a set of proteins that function at the ribosome, during protein synthesis, to facilitate translational elongation from the formation of the first to the last peptide bond of a growing polypeptide. ... Elongation is the most rapid step in translation.

Which of the following elongation factor can be referred to as Translocase?

EF-G (elongation factor G, historically known as translocase) is a prokaryotic elongation factor involved in protein translation. As a GTPase, EF-G catalyzes the movement (translocation) of transfer RNA (tRNA) and messenger RNA (mRNA) through the ribosome.

What happens during elongation of transcription?

Basically, elongation is the stage when the RNA strand gets longer, thanks to the addition of new nucleotides. During elongation, RNA polymerase "walks" along one strand of DNA, known as the template strand, in the 3' to 5' direction.