• BMB Reports
• /
• 제55권7호
• /
• pp.316-322
• /
• 2022

Ubiquitin is relatively modest in size but involves almost entire cellular signaling pathways. The primary role of ubiquitin is maintaining cellular protein homeostasis. Ubiquitination regulates the fate of target proteins using the proteasome- or autophagy-mediated degradation of ubiquitinated substrates, which can be either intracellular or foreign proteins from invading pathogens. Legionella, a gram-negative intracellular pathogen, hinders the host-ubiquitin system by translocating hundreds of effector proteins into the host cell's cytoplasm. In this review, we describe the current understanding of ubiquitin machinery from Legionella. We summarize structural and biochemical differences between the host-ubiquitin system and ubiquitin-related effectors of Legionella. Some of these effectors act much like canonical host-ubiquitin machinery, whereas others have distinctive structures and accomplish non-canonical ubiquitination via novel biochemical mechanisms.

• BMB Reports
• /
• 제41권1호
• /
• pp.35-40
• /
• 2008

The molten globular conformation of V26A ubiquitin (valine to alanine mutation at residue 26) was studied by nuclear magnetic resonance spectroscopy in conjunction with amide hydrogen/deuterium exchange. Most of the amide protons that are involved in the native secondary structures were observed to be protected in the molten globule state with the protection factors from 1.2 to 6.7. These protection factors are about 2 to 6 orders of magnitude smaller than those of the native state. These observations indicate that V26A molten globule has native-like backbone structure with marginal stability. The comparison of amide protection factors of V26A ubiquitin molten globule state with those of initial collapsed state of the wild type ubiquitin suggests that V26A ubiquitin molten globule state is located close to unfolded state in the folding reaction coordinate. It is considered that V26A ubiquitin molten globule is useful model to study early events in protein folding reaction.

• Journal of Applied Biological Chemistry
• /
• 제43권1호
• /
• pp.1-4
• /
• 2000

Chloramphenicol acetyl CoA transferase (CAT) and angiotensin- converting enzyme inhibitory peptide (ACEI) were fused to C-terminal region of rice ubiquitin to examine the level of transcripts or enzyme activities in yeast. When two chimeric genes under an inducible Gall promoter control were transformed into Saccharomyces cerevisaie, both CAT and ACE inhibitory activities were enhanced by three to four-fold as compared to those containing no ubiquitin gene. However, the levels of transcripts of ubiquitin fused and un fused genes were not significantly different each other. Therefore, it was suggested that the expression of foreign genes was post-transcriptionally enhanced by fusion of plant ubiquitin in heterologous organisms such as yeast.

• 한국육종학회지
• /
• 제42권4호
• /
• pp.339-343
• /
• 2010

Post-translational covalent modifications by small molecules or peptides remodel target proteins. One such modification, made by ubiquitin or small ubiquitin-related modifier (SUMO), is a rapidly expanding field in cell signaling pathways. Ubiquitin attachment controls the turnover and degradation of target proteins while SUMO conjugation regulates their activity and function. Recent studies report many examples of cross-talk between ubiquitin and SUMO pathways, indicating that the boundary is no longer clear. Here, we review recent progress concerning how ubiquitin and SUMO participate in new regulatory roles in plant cell, and how ubiquitination and sumoylation control plant growth and development.

• BMB Reports
• /
• 제37권6호
• /
• pp.676-683
• /
• 2004

The conformational properties of hydrophobic core variant ubiquitin (Val26 to Ala mutation) in an acidic solution were studied. The intrinsic tryptophan fluorescence emission spectrum, far-UV and near-UV circular dichroic spectra, the fluorescence emission spectrum of 8-anilinonaphthalene-1-sulfonic acid in the presence of V26A ubiquitin, and urea-induced unfolding measurements indicate this variant ubiquitin to be in the partially folded molten globule conformation in solution at pH 2. The folding kinetics from molten globule to the native state was nearly identical to those from the unfolded state to the native state. This observation suggests that the equilibrium molten globule state of hydrophobic core variant ubiquitin is an on-pathway folding intermediate.

• Mycobiology
• /
• 제39권4호
• /
• pp.243-248
• /
• 2011

The ubiquitin-proteasome system is one of the major protein turnover mechanisms that plays important roles in the regulation of a variety of cellular functions. It is composed of E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 ubiquitin ligases that transfer ubiquitin to the substrates that are subjected to degradation in the 26S proteasome. The Skp1, Cullin, F-box protein (SCF) E3 ligases are the largest E3 gene family, in which the F-box protein is the key component to determine substrate specificity. Although the SCF E3 ligase and its F-box proteins have been extensively studied in the model yeast Saccharomyces cerevisiae, only limited studies have been reported on the role of F-box proteins in other fungi. Recently, a number of studies revealed that F-box proteins are required for fungal pathogenicity. In this communication, we review the current understanding of F-box proteins in pathogenic fungi.

• Applied Biological Chemistry
• /
• 제47권1호
• /
• pp.33-40
• /
• 2004

Ubiquitin 폴딩 반응의 초기에 나타나는 transient 폴딩 intermediate 상태의 열역학적인 특성을 연구하였다. 온도와 화학변성제의 농도를 바꾸어주면서 측정한 폴딩 kinetics의 결과로부터 unfolded 상태와 intermediate 상태의 평형상수 및 자유에너지를 quantitative kinetic modeling을 통하여서 구하였으며 또한 온도에 따른 자유에너지의 변화로부터 unfolded 상태에서 intermediate 상태로 전환될 때의 열역학적 함수인 ${\Delta}H,\;{\Delta}S,\;{\Delta}C_p$를 구하였다. Ubiquitin이 unfolded 상태에서 intermediate 상태가 될 때의 ${\Delta}C_p$는 unfolded 상태에서 native 상태로 되는 과정의 ${\Delta}C_p$의 약 80% 정도 되었다. 이것은 intermediate가 native 상태에 가까운 매우 조밀한 구조를 이루고 있는 ensemble state임을 나타낸다. 상온에서의 ${\Delta}H$는 양의 값을 보였다. 이는 ubiquitin의 unfolded 상태에서 소수성 잔기 주위에 위치한 물 분자의 규칙적인 구조가 intermediate 상태가 될 때 와해되기 때문이라고 여겨진다. 이러한 양의 enthalpy는 자유로워진 물 분자에 의한 전체 계의 entropy의 증가에 의하여서 보상되어 unfolded 상태에서intermediate 상태로의 전환은 음의 자유에너지를 갖게 되며 폴딩 반응의 초기에 관찰되는 것으로 여겨진다.

• Molecules and Cells
• /
• 제19권2호
• /
• pp.228-231
• /
• 2005

Recent characterization of several genes involved in plant defense responses suggested that ubiquitin-mediated protein degradation has a role in these responses. We isolated two cDNAs (NtUBA1 and NtUBA2) encoding ubiquitin-activating enzyme (E1) from Nicotiana tabacum cv. BY-2. The open reading frames of both encoded 1080 amino acids, corresponding to molecular masses of 120 kDa. The E1s and corresponding transcripts were upregulated by infection with tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV), and to a lesser extent by cucumber mosaic virus (CMV). Furthermore, they were also upregulated by wounding stress, and the plant hormones salicylic acid, jasmonic acid and the ethylene precursor, aminocyclopropane-1-carboxylic acid (ACC). Our findings support the idea that the ubiquitin-proteasome system plays a role in plant disease defenses.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2003년도 생물공학의 동향(XII)
• /
• pp.554-556
• /
• 2003

본 연구에서는 고부가가치 의약단백질인 human growth hormone을 고순도로 얻기 위하여 재조합 대장균을 이용하여 ubiquitin이 융합된 형태로 단백질을 발현시키고, 이를 분해하는 ubiquitin-specific pretense를 발현시켜 이를 분리 ${\cdot}$ 정제하고 효소특성을 살펴보았다. UBP1 enzyme을 재조합 대장균을 이용하여 발현하고 분리 ${\cdot}$ 정제한 결과, 분자량은 약 83.5kDa이었으며, $40^{\circ}C$, pH 8.0에서 최대 효소활성을 보였다.

• International Journal of Industrial Entomology and Biomaterials
• /
• 제2권1호
• /
• pp.61-64
• /
• 2001

Ubiquitin can be covalently attached to cellular proteins as a post-translational modification rind is involved in metabolic stresses, such as bent shock and immune response. We have isolated and sequenced a cDNA encoding ubiquitin from the silkworm, Bombyx mori. The insert in the clone is 533 nucleotide long with an open reading frame of 387 nucleotides that encodes a protein of 129 amino acids with a molecular weight of 14.8 kDa. The amino acid sequence shared high homology with the ubiquitins known so far, The result of dot blot hybridization showed that the B. mori ubiquitin gene is up-regulated upon f. rofi infection, suggesting that the B. mori ubiquitin plays an immune-related role.