Do DNA ligases have the ability to link single stranded DNA?

There are two answers online, Tianya and many other places. It's all the same. I agree with the following one, but I'd better check the literature and ask the teacher to figure it out before you. :

Please wait. No. 1. General nature:

The DNA ligase of E. coli is a polypeptide chain with a molecular weight of 75 kd. Sensitive to trypsin and can be hydrolyzed by it. The small fragments formed after hydrolysis are still partially active and can catalyze the reaction of enzymes with NAD (but not ATP) to form enzyme-AMP intermediates, but cannot continue to transfer AMP to DNA to promote phosphodiester bond formation.

DNA ligase has about 300 molecules in E. coli cells, which is similar to the number of molecules of DNA polymerase, which is also a reasonable phenomenon. Because the main function of DNA ligase is to seal the gap in the DNA duplex after the DNA polymerase catalyzes polymerization, filling the single-strand gap on the double-stranded DNA. This plays an important role in DNA replication, repair, and recombination, and mutant strains with defective ligases cannot undergo DNA replication, repair, and recombination.

The bacteriophage T4DNA ligase molecule is also a polypeptide chain with a molecular weight of 60 kD, and its activity is easily inhibited by KCl and spermine. The catalytic process of this enzyme requires ATP assistance. T4DNA ligase ligates DNA-DNA, DNA-RNA, RNA-RNA, and double-stranded DNA sticky or blunted ends.

In addition, NH4C1 can increase the catalytic rate of E. coli DNA ligase, but not T4DNA ligase. Neither T4DNA ligase nor E. coli DNA ligase can catalyze the ligation of two free DNA strands. 2. Mechanism of action:

DNA ligases use the energy in NAD or ATP to catalyze the formation of phosphodiester bonds between two nucleic acid strands. The reaction process can be divided into three steps: (1) NAD or ATP transfers its adenylyl group to an amino group of a lysine residue of DNA ligase to form a covalent enzyme-adenylate intermediate, while releasing nicotinamide mononucleotide (NMN) or pyrophosphate.

2) Retransfer the adenylyl group on the enzyme-adenylate intermediate to 5 of DNA'- phosphate terminus, which forms a pyrophosphoryl derivative, i.e., DNA-adenylate; (3) This activated 5'- Phosphoryl terminus can be and DNA3'The phosphodiester bond is synthesized by the -OH terminal reaction, and AMP is released at the same time. The entire process catalyzed by DNA ligase is reversible. Enzyme-adenylate intermediates can react with NMN or PPI to generate NDA or ATP and free enzymes; DNA-adenylate can also react with NMN and free enzymes to regenerate NAD.

This reverse reaction process allows covalent closed-loop supercoiled DNA to be catalyzed by ligases in the presence of AMP to produce nicked DNA-adenylylate to generate relaxed closed-loop DNA.

No, it works as a hydrogen bond between them.

The role of DNA ligase is (Senyan).

a.Cut off and straighten out the DNA strand during replication.

Ligation DNA after primer removal

c.Unwrap the DNA double helix.

d.Ligation of adjacent DNA strands3'-oh and 5'-p

The answer is to connect the adjacent DNA strands3'-oh and 5'-p

1: Conclusion: DNA ligase is mainly used for genetic engineering, which recombines the sticky ends "cut" by restriction endonucleases, so it is also called "gene needle and thread".As long as it is DNA, it can be linked, regardless of single and double strands.

2 : Extension: DNA ligase, also known as DNA adhesivease, plays a special and crucial role in molecular biology, that is, the bonding of two pieces of DNA into one.

Whether it is a double-stranded or single-stranded DNA bond, DNA binase can bind DNA to 3 by forming phosphodilipid bonds'The tail end of the end is the same as 5'The front ends of the end are connected together.

DNA ligases are not specific, and restriction enzymes are.

DNA ligases are attached to phosphodiester bonds. Not hydrogen bonds between bases. So DNA ligase has no specificity. (The hydrogen bonds between the bases do not require any enzymes to connect, they are automatically linked).

DNA ligase, also known as DNA ligase, plays a special and critical role in molecular biology by connecting the 3'-OH end of the DNA strand and the 5'-p end of the other DNA strand to form phosphodiester bonds, thus connecting two adjacent DNA strands into a complete strand. The catalytic action of ligase requires the consumption of ATP.

Based on this problem, I thought about it for a long time, and I moved all the textbooks out, it seems that the vacation has been too long, and my memory is not good, well, I just graduated this year.

I don't even understand what the first one said, why it is called not hydrogen bonding, there is no specificity.

The role of DAN ligase is to form phosphodiester bonds, and although the sequences recognized by the restriction enzymes are different, the notch of the ligase ligation is the same.

So no. Yes.

Hope, after all, people have spent... Hee-hee.

DNA ligases are attached to phosphodiester bonds. Not hydrogen bonds between bases. So DNA ligase has no specificity.

Yes, identify specific nucleotide sequences.

If not, there will be restriction enzymes.

DNA replication is actually semi-discontinuous replication -- that is, the synthesis of only one strand is continuous, which sounds amazing, but it is true, that the chain of continuous synthesis is called the leading strand, and the other strand is called the subsequent strand, and its synthesis is discontinuous, and the synthesis that uses it as a template needs to be done piece by piece, and the fragment that is synthesized is called the Okazaki fragment.

The reason for this phenomenon is that DNA synthase can only follow 5'-3'The two strands of DNA itself are reversed, so that only one strand can be synthesized continuously (the direction of the daughter strand generated by it as a template is exactly what the DNA polymerase can directly provide), and then the strand has to be coiled into a loop, reversed, and then synthesized with the strand.

At the beginning of resynthesis, DNA polymerase requires a piece of RNA primer, which in prokaryotes is produced by DNAQ (an enzyme) in a single strand5 that has been unwinded'Because the synthesis of the subsequent strand is not continuous, each fragment has to have primers, and at the end of DNA synthesis, these primers are excised, leaving a gap, and then a specific enzyme is needed to fill the gap (such as DNA polymerase I in Escherichia coli), but there is a gap between the filling sequence and the surrounding sequence, that is, 3 at their junction'-5'The phosphodiel bond is broken, and this is where the DNA ligase comes into play to connect it.

So, there are a lot of notches on the trailing strand that is really enough for the DNA ligase to be busy for a while, and only the RNA primers on the leading strand are there at the beginning, so in the end, this is basically the only place where ligase is used.

DNA ligases are divided into two categories: the commonly used E·colidna ligase (isolated from E. coli) and T4DNA ligase (isolated from T4 bacteriophage).

Hello, (1) E·Coli DNA ligase, ** in Escherichia coli, can be used to attach sticky ends;

2) T4DNA ligase: ** is a T4 bacteriophage that can be used to attach sticky ends and blunt ends, but the ligation efficiency is low.

3) Thermostable DNA ligase (ThermostableDNALIGASE) is a nuclease isolated and purified from the thermoactinomycesthermophilus strain, which can catalyze the ligation of two oligonucleotide probes at high temperatures.