• BMB Reports
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• 제57권1호
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• pp.40-49
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• 2024

Prokaryotes encode clustered regularly interspaced short palindromic repeat (CRISPR) arrays and CRISPR-associated (Cas) genes as an adaptive immune machinery. CRISPR-Cas systems effectively protect hosts from the invasion of foreign enemies, such as bacteriophages and plasmids. During a process called 'adaptation', non-self-nucleic acid fragments are acquired as spacers between repeats in the host CRISPR array, to establish immunological memory. The highly conserved Cas1-Cas2 complexes function as molecular recorders to integrate spacers in a time course manner, which can subsequently be expressed as crRNAs complexed with Cas effector proteins for the RNA-guided interference pathways. In some of the RNA-targeting type III systems, Cas1 proteins are fused with reverse transcriptase (RT), indicating that RT-Cas1-Cas2 complexes can acquire RNA transcripts for spacer acquisition. In this review, we summarize current studies that focus on the molecular structure and function of the RT-fused Cas1-Cas2 integrase, and its potential applications as a directional RNA-recording tool in cells. Furthermore, we highlight outstanding questions for RT-Cas1-Cas2 studies and future directions for RNA-recording CRISPR technologies.

• The Plant Pathology Journal
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• 제38권1호
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• pp.12-24
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• 2022

In this study, we conducted whole-genome sequencing with six species of Pectobacterium composed of seven strains, JR1.1, BP201601.1, JK2.1, HNP201719, MYP201603, PZ1, and HC, for the analysis of pathogenic factors associated with the genome of Pectobacterium. The genome sizes ranged from 4,724,337 bp to 5,208,618 bp, with the GC content ranging from 50.4% to 52.3%. The average nucleotide identity was 98% among the two Pectobacterium species and ranged from 88% to 96% among the remaining six species. A similar distribution was observed in the carbohydrate-active enzymes (CAZymes) class and extracellular plant cell wall degrading enzymes (PCWDEs). HC showed the highest number of enzymes in CAZymes and the lowest number in the extracellular PCWDEs. Six strains showed four subsets, and HC demonstrated three subsets, except hasDEF, in type I secretion system, while the type II secretion system of the seven strains was conserved. Components of human pathogens, such as Salmonella pathogenicity island 1 type type III secretion system (T3SS) and effectors, were identified in PZ1; T3SSa was not identified in HC. Two putative effectors, including hrpK, were identified in seven strains along with dspEF. We also identified 13 structural genes, six regulator genes, and five accessory genes in the type VI secretion system (T6SS) gene cluster of six Pectobacterium species, along with the loss of T6SS in PZ1. HC had two subsets, and JK2.1 had three subsets of T6SS. With the GxSxG motif, the phospholipase A gene did locate among tssID and duf4123 genes in the T6SSa cluster of all strains. Important domains were identified in the vgrG/paar islands, including duf4123, duf2235, vrr-nuc, and duf3396.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1045-1049
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• 2005

In this paper, the dynamic crawling of a five-bar planar mechanism is investigated. One complete cycle of the crawling selected in this study consists of four different steps, i) sliding at one contact point between the mechanism and the ground, ii) changing its configuration without sliding at two contact points, iii) sliding at the other contact point, and iv) again changing its configuration without sliding at two contact points. In this type of crawling, the crawling mechanism maintains the shape of the parallel structure throughout a complete crawling cycle. The modeling algorithm for serial manipulators proposed by M. Thomas and et al.[1] is employed by introducing imaginary joints and links which represent the contact interfaces between the one end of the mechanism and the ground, while the other end of the mechanism is regarded as an end-effector of the imaginary serial manipulator which treats the reaction force and torque at the contact point as external forces. Then, a complete cycle of dynamic crawling of the mechanism is investigated through various computer simulations. The simulation result show that the stable crawling characteristics of the mechanism could be secured when the proper configurations depending on specified frictional constraints are met.

• 미생물학회지
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• 제50권3호
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• pp.245-248
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• 2014

Pseudomonas syringae pv. actinidiae는 참다래 속(genus Actinidia) 식물에 궤양병을 일으키는 원인세균이다. 7개의 필수 유전자와 11개의 타입 III 효과기 유전자에 대한 다중염기서열 분석을 통해 전 세계 여러 곳에서 분리된 병원성 균주들은 세 그룹으로 나눌 수 있었고 각각 Psa1-Psa3 그룹으로 명명되었다. 본 연구에서는 3개의 Psa1, 3개의 Psa2 및 우리나라와 이탈리아에서 분리된 3개씩의 Psa3 균주 등 총 12 균주를 대상으로 그룹별 표현형을 비교하였다. 그 결과 모든 그룹의 균주가 $22^{\circ}C$ 이하에서 최대의 성장을 보였으며, Psa3 균주들은 $30^{\circ}C$ 이상의 온도에서 성장이 정지되었다. 또한 우리나라의 Psa3 균주의 지연기가 이탈리아 Psa3 균주 보다 긴 특징을 보였다. API 20NE 시험에서 Psa2 균주는 potassium gluconate, capric acid 및 trisodium citrate를 이용하지 못하는 점에서 Psa1과 Psa3 균주와 구별되었다. 다른 그룹과 달리 우리나라 Psa3 균주는 esculin을 가수분해할 수 있었다. API ZYM 시험에서는 Psa3에 속하는 균주들에서만 ${\beta}$-glucosidase 활성이 있는 것으로 나타났다. Psa 그룹에 따라 ampicillin, novobiocin 및 oleandomycin 등의 항생물질에 대한 민감성 양상이 서로 달랐다.