Cooccurring Activities of Two Autotrophic Pathways in Symbionts of the Hydrothermal Vent Tubeworm Riftia pachyptila
Cooccurring Activities of Two Autotrophic Pathways in Symbionts of the Hydrothermal Vent Tubeworm Riftia pachyptila
复制标题
DOI：
10.1128/aem.00794-21
复制
发表时间：
2021-09-01
影响因子：
4.4
通讯作者：
Scott，Kathleen M.
中科院分区：
文献类型：
--
作者：
Leonard，Juliana M.;Mitchell，Jessica;Scott，Kathleen M.
基因组和蛋白质组数据预测存在还原性柠檬酸循环（rCAC;也称为还原性三羧酸循环）和Calvin-Benson-Bassham循环（CBB）在“EscheridatusEndoriftia persephonae”中，来自巨大热液喷口管虫Riftia pachyptila的自养硫氧化细菌内共生体。我们测试了这些周期是否由硫化物供应差异诱导，因为由rCAC的生物合成中间体的合成比由CBB的能量更便宜。R.在高压水族箱中，在低（28 ~ 40 μmol · h-1）或高（180 ~ 276 μmol · h-1）硫化物供应速率下，在原位条件下孵育厚尾藻。从R.在两种条件下保持的pachyptilamaCO 2固定率相似。rCAC酶ATP依赖性柠檬酸裂解酶（ACL）和CBB酶1，3-二磷酸羧化酶/加氧酶（RubisCO）的活性在两种条件下没有差异，尽管ATP依赖性柠檬酸裂解酶的转录丰度在低硫化物条件下高4至5倍。内部溶解无机碳（DIC）库的δ 13 C值变化较大，与硫化物供应速率无关。从新鲜采集的R.厚膜虫的δ 13 C值介于rCAC和CBB法测定的值之间。这些观察结果是一致的rCAC和CBB在此共生共存的活动。IMPORTANCEPrevious本研究中，活动的rCAC和CBB在R。pachyptila主要是从R. pachyptila没有直接评估在现场条件之前收集。在本研究中，R. pachyptila保持和监测高压水族馆之前，测量其CO2固定参数。结果表明，硫化物浓度的范围类似于那些experiencedin situeddo不施加强烈的影响，相对活性的rCAC和CBB。这一观察结果强调了进一步研究这种共生关系和其他具有多种CO2固定途径的生物的重要性，最近的基因组学和生物化学研究表明，这种共生关系可能比预期的更普遍。
Genome and proteome data predict the presence of both the reductive citric acid cycle (rCAC; also called the reductive tricarboxylic acid cycle) and the Calvin-Benson-Bassham cycle (CBB) in “CandidatusEndoriftia persephonae,” the autotrophic sulfur-oxidizing bacterial endosymbiont from the giant hydrothermal vent tubeworm Riftia pachyptila. We tested whether these cycles were differentially induced by sulfide supply, since the synthesis of biosynthetic intermediates by the rCAC is less energetically expensive than that by the CBB. R. pachyptila was incubated underin situconditions in high-pressure aquaria under low (28 to 40 μmol · h−1) or high (180 to 276 μmol · h−1) rates of sulfide supply. Symbiont-bearing trophosome samples excised fromR. pachyptilamaintained under the two conditions were capable of similar rates of CO2fixation. Activities of the rCAC enzyme ATP-dependent citrate lyase (ACL) and the CBB enzyme 1,3-bisphosphate carboxylase/oxygenase (RubisCO) did not differ between the two conditions, although transcript abundances for ATP-dependent citrate lyase were 4- to 5-fold higher under low-sulfide conditions. δ13C values of internal dissolved inorganic carbon (DIC) pools were varied and did not correlate with sulfide supply rate. In samples taken from freshly collectedR. pachyptila, δ13C values of lipids fell between those collected for organisms using either the rCAC or the CBB exclusively. These observations are consistent with cooccurring activities of the rCAC and the CBB in this symbiosis.IMPORTANCEPrevious to this study, the activities of the rCAC and CBB inR. pachyptilahad largely been inferred from “omics” studies ofR. pachyptilawithout direct assessment ofin situconditions prior to collection. In this study,R. pachyptilawas maintained and monitored in high-pressure aquaria prior to measuring its CO2fixation parameters. Results suggest that ranges in sulfide concentrations similar to those experiencedin situdo not exert a strong influence on the relative activities of the rCAC and the CBB. This observation highlights the importance of further study of this symbiosis and other organisms with multiple CO2-fixing pathways, which recent genomics and biochemical studies suggest are likely to be more prevalent than anticipated.