Fourteen full-length infectious genomes extracted from this plant were directly cloned and sequenced. This experimental system, which can be transferable to other geminiviruses, was validated by analysis of the phenotypic effect of mutations appearing in TYLCV genomes in a single tomato host plant originally inoculated with a unique viral sequence. A binary vector containing this 41-nt region and a unique restriction site was created, allowing direct cloning of infectious monomeric viral genomes provided that they harbour the same restriction site at the corresponding nucleotide position.
Using Tomato yellow leaf curl virus (TYLCV), we show here that infectivity can be obtained when only a 41-nucleotide region containing a highly conserved stem-loop is repeated.
However, the phenotypic effects of naturally occurring mutations have never been extensively investigated in geminiviruses, particularly because, to be infectious, cloned viral genomes usually require sub-cloning as complete or partial tandem repeats into a binary vector from Agrobacterium tumefaciens. Previous studies have shown that geminiviruses and RNA viruses exhibit similar mutation frequencies, although geminiviruses are replicated by host DNA polymerases and RNA viruses by their own virus-encoded error-prone RNA-dependent RNA-polymerase. To avoid these, follow the recommended guidelines for storage and reactions, and always check for the efficacy of digestion along with purification of digested products on an agarose gel.Viruses of the genus Begomovirus ( Geminiviridae) are emerging economically important plant viruses with a circular, single-stranded DNA genome. Star activity (or off-target cleavage) and incomplete cleavage are potential challenges which may occur due to suboptimal enzymatic conditions or inappropriate enzyme storage. For complete digestion, make sure that the enzyme volume is 1/10th of the total reaction volume, the optimal temperature is constantly maintained throughout the reaction, the total reaction time is appropriately calculated based on the amount of DNA to be digested, appropriate buffers should be used to ensure maximal enzymatic activity, and in case of a double digest, make sure that the two restriction sites are far enough so that the activity of one enzyme cannot interfere with the activity of the other. Always use a control DNA digestion with the enzyme to ensure adequate activity (to avoid interference due to high glycerol in the enzyme). The enzyme should always be stored at -20C and multiple freeze-thaw cycles should be avoided in order to maintain optimal activity. The most common challenges with restriction digest include- 1. The four most common types of restriction enzymes include: Type I (cleaves at sites remote from a recognition site), Type II (cleaves within or at short specific distances from a recognition site), Type III (cleave at sites a short distance from a recognition site), and Type IV (targets modified DNA- methylated, hydroxymethylated and glucosyl-hydroxymethylated DNA).
Restriction Enzymes NotI A restriction enzyme or restriction endonuclease is defined as a protein that recognizes a specific, short nucleotide sequence and cuts the DNA only at or near that site, known as restriction site or target sequence.
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